Microscopic simulation of quantum dynamics and nuclear tunneling in bacterial reaction centers

The dispersed polaron version of the semiclassical trajectory approach is used to evaluate the quantum mechanical nuclear tunneling effects in the charge recombination reaction, P⁺Q^–PQ, in photosynthetic bacterial reaction centers, The cclculations are based on the crystallographic structure of reaction centers from Rhodopseudomonas viridis. They succeed in capturing the temperature dependence of the rate constant without using adjustable parameters. This provides the first example of a microscopic simulation of quantum mechanical nuclear tunneling in a biological system.Abbreviations P bacteriochlorophyll dimer - Q ubiquinone in Rhodobacter sphaeroides, menaquinone in Rhodopseudomonas viridis - Rps. Rhodopseudomonas - Rb. Rhodobacter - QCFF/PI quantum mechanical extension of the consistent force field to -electron     

Mechanism of catalase induction in Rhodopseudomonas spheroides: Role of porphyrin excretion

Summary Catalase induction in Rhodopseudomonas spheroides and three locally isolated strains of Rhodopseudomonas (TL-1, TL-4 and Rps. D) was studied. A correlation between the rate of excretion of porphyrin and the inducibility of the culture was observed. 8-hydroxyquinoline at 4x10^-5 M had no effect on Bchl synthesis but it inhibited porphyrin excretion and catalase induction in Rhodopseudomonas spheroides. 8-OH Q at this concentration partially inhibited Bchl synthesis and catalase induction in strain TL-1. The data indicate that the amount of catalase produced is dependent on the pool size of porphyrins.Abbreviations used ALA -amino laevulinic acid - Bchl Bacteriochlorophyll - EDTA Ethylene diamine tetra acetate - DMSO Dimethyl sulfoxide - 8-OH Q 8-hydroxyquinoline - nm nanometer - Rh. Rhodopseudomonas This work is part of a thesis submitted by K. T. Shanmugam in partial fulfillment of the requirements for the Ph. D. degree.     

Untersuchungen zur Adsorption des Bacteriophagen Rp 1 an Rhodopseudomonas palustris 1 e 5

Zusammenfassung Adsorptionskinetiken mit verschiedenen Rhodopseudomonas palustris-Stämmen ergaben, daß Rp 1-Phagen nur an Stamm 1 e 5 adsorbieren. Als Adsorptionskonstante wurde ein Wert von K=3,8·10^-10 ml/min ermittelt. Während des Wachstums der Wirtsbakterien werden die Rp 1-Phagen nur in der Teilungsebene und an einem Zellpol adsorbiert. Die Phagen adsorbieren auch an den intracytoplasmatischen Membranen. Die Spezifität dieser Adsorption wird diskutiert.

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Investigations on the adsorption of the bacteriophage Rp1 to Rhodopseudomonas palustris 1 e 5

Summary The adsorption of the bacteriophage Rp 1 is restricted to cells of the strain 1 e 5 of Rhodopseudomonas palustris. The adsorption constant was found to be K=3.8·10^-10 ml/min. During the growth phase of the host bacterium Rp 1 is only adsorbed to one of the cell poles and the division plain of the cells. In addition, the phage is adsorbed to the intracytoplasmic membranes. The specifity of this adsorption is discussed.

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Abkürzungen pfu plaque forming units - Rps. Rhodopseudomonas - R. Rhodospirillum     

Trennung der Thylakoidbausteine einiger Athiorhodaceae durch Gelelektrophorese

Zusammenfassung Thylakoide vonRhodospirillum rubrum, Rhodopseudomonas viridis undRhodopseudomonas capsulata wurden durch Behandlung mit Phenol-Ameisensäure in makromolekulare, in der Gelelektrophorese wandernde Fraktionen aufgespalten. Dabei ergaben sich vier deutlich hervortretende Hauptfraktionen, die zum Teil noch in Unterfraktionen aufzulösen sind.BeiRhodospirillum rubrum wurden neben den Thylakoiden auch noch Rohfraktionen der cytoplasmatischen Membran und der Zellwand mit der gleichen Methode untersucht. Alle Strukturen unterschieden sich deutlich voneinander in der Zahl und Wanderungsgeschwindigkeit ihrer Banden.Aus einer Dunkelkultur vonRhodospirillum rubrum, in der durch Absenken des Sauerstoffpartialdruckes die Thylakoidmorphogenese und Pigmentsynthese induziert worden war, wurde die Gesamtmembranfraktion isoliert, durch Behandlung mit Phenol-Ameisensäure dissoziiert und gelelektrophoretisch aufgetrennt. In den Pherogrammen war deutlich von Beginn der Induktion an eine Zunahme thylakoidspezifischer Bandenmuster zu erkennen. Ein Ausplanimetrieren der Absorptionskurven ergab, daß das Wachstum der Thylakoidstrukturen exponentiell erfolgte. Unter den Bedingungen der Kultur wurde nach etwa 8 Std ein Plateau in der Ausbildung der thylakoidspezifischen Strukturen erreicht. Die Kurve der Bacteriochlorophyllsynthese nahm einen etwas anderen Verlauf. Sie war im Bereich des exponentiellen Wachstums der Thylakoidstrukturen stärker gekrümmt, bog dann aber später ebenfalls ab, so daß sie nach 8–10 Std parallel zu den Thylakoiden verlief.

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Fractionation of thylakoid-components of some athiorhodaceae by polyacrylamide-gel electrophoresis

Summary Thylakoids (chromatophores) ofRhodospirillum rubrum, Rhodopseudomonas viridis, andRhodopseudomonas capsulata were fractionated after treatment with phenol-formic acid-water (2:1:1) by gel electrophoresis in four main fractions. The pattern of maxima was different in the three species.Crude preparations of cytoplasmic membrane and cell wall ofR. rubrum differ from the thylakoids in their pattern of electrophoresis distribution.Crude total membrane fractions were isolated from cells ofR. rubrum, which was induced to synthesize bacteriochlorophyll and thylakoids.Fractionation of the membranes by the above mentioned method shows very clearly that after induction of morphogenesis the thylakoid-specific membrane units are increased exponentially.

     

Verwertung von Trimethylammoniumverbindungen durch Acinetobacter calcoaceticus

Zusammenfassung Die Verwertung von Carnitin und Carnitinderivaten (O-Acylcarnitine, Carnitincarboxyl-derivate) und strukturverwandten Trimethylammoniumverbindungen (Betaine und Stickstoffbasen) durch Acinetobacter calcoaceticus wurde anhand des Wachstums und des quantitativen Nachweises der Metabolite untersucht. Der Stamm wuchs auf l-Carnitin, l-O-Acylcarnitinen und -Butyrobetain als jeweils einziger C-Quelle. Der Verbrauch dieser Verbindungen und das Wachstum korrelierten mit der Spaltung der C-N-Bindung und mit dem gebildeten Trimethylamin. d-Carnitin wurde metabolisiert, wenn als zusätzliche C-Quelle l-Carnitin im Nährmedium vorhanden war, oder wenn die Bakterien mit l-oder dl-Carnitin vorinkubiert worden waren. Mit d-Carnitin als einziger C-Quelle wuchsen die Bakterien jedoch nicht. Die Bakterien oxidierten Cholin zu Glycinbetain in Gegenwart einer zusätzlichen C-Quelle, Glycinbetain selbst wurde nicht assimiliert. In Hinsicht auf den Abbau quaternärer Stickstoffverbindungen besitzt Acinetobacter calcoaceticus im Vergleich zu anderen Carnitin-verwertenden Bakterienarten einen für ihn charakteristischen Stoffwechselweg.

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Utilization of trimethylammonium-compounds by Acinetobacter calcoaceticus

The utilization of carnitine and carnitine derivatives (O-acylcarnitines, carnitine carboxylderivatives) and structure-related trimethylammonium-compounds (betaines and nitrogen-bases) by Acinetobacter calcoaceticus was studied by means of the control of growth and the quantitative detection of metabolites. The strain grew only on l-carnitine, l-O-acylcarnitines, and -butyrobetaine as the sole carbon sources. The utilization of these compounds and the growth correlated with the cleavage of the C-N bond and thereby with the formation of trimethylamine. d-Carnitine was metabolized, if an additional carbon source, like l-carnitine, was present in the incubation mixture, or if the bacteria were preincubated with l-or dl-carnitine, but no growth was observed on d-carnitine as the sole carbon source. The bacteria oxidized choline to glycinebetaine in the presence of additional carbon sources, glycinebetaine itself was not assimilated. With regard to the catabolism of quaternary nitrogen compounds Acinetobacter calcoaceticus shows a different pathway in comparison with other bacterial species metabolizing carnitine.

     

Der Geißelapparat von Rhodopseudomonas palustris

Zusammenfassung Das Molekulargewicht der Flagellin-Moleküle der Rhodopseudomonas palustris-Geißeln konnte durch Ultrazentrifugation zu MG=15500 bestimmt werden; die Gelelektrophorese lieferte den sechsfachen Wert (MG=93000).Die Flagellin-Moleküle sind gekennzeichnet durch einen sehr hohen Gehalt an Serin, Threonin, Asparaginsäure, Glycin, Alanin und Leucin. Verglichen mit Flagellin-Molekülen anderer Bakterien ist der molare Gehalt des Rhodopseudomonas palustris-Flagellins an Serin, Threonin und Glycin ungewöhnlich hoch, der Gehalt an Glutaminsäure und Arginin relativ niedrig. Das Flagellin-Molekül ist aus 158 Aminosäuren aufgebaut.Geißelfilament und Geißelhaken unterscheiden sich durch ihren Protein- und Serin-Gehalt. Der Geißelhaken enthält voraussichtlich zwei Proteinkomponenten: Flagellin-Moleküle, die das Geißelhaken-(und Geißelfilament-)core aufbauen, und Flagellin-Moleküle, die das central core des Geißelhakens bilden. Das central core-Flagellin weist einen 45% höheren Seringehalt als das core-Flagellin auf.Es wird die Hypothese aufgestellt, daß der hohe Seringehalt der central core-Untereinheiten verantwortlich ist für die Stabilität des Geißelhakens durch Ausbildung von Wasserstoffbrücken. Ebenfalls wird vermutet, daß der sehr hohe Gehalt des Rhodopseudomonas palustris-core-Flagellins an OH-Gruppen tragenden Aminosäuren eine Bindung der Scheidenuntereinheiten bewirkt.

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The flagellar apparatus of Rhodopseudomonas palustris VI. Characterization of flagellin

Summary Flagellin molecules of Rhodopseudomonas palustris have a molecular weight of 15,500 when they are determined in the analytical ultracentrifuge. But when the method of electrophoresis in polyacrylamide gels is used, their molecular weight is 93,000.Flagellin molecules are characterized by a high content of serine, threonine, aspartic acid, glycine, alanine, and leucine. In comparison with the flagellin molecules of other bacteria those of Rhodopseudomonas palustris contain extremely high values of serine, threonine and glycine while the proportion of glutamic acid and arginine is relatively low. The flagellin molecule is built up of 158 amino acids.The flagellar filament and the flagellar hook differ in content of total protein and of serine. The flagellar hook probably contains two protein components: one kind of molecule constitutes the core of the hook; an other kind of flagellin molecule is present in the central core. The serine content of flagellin of the central core is 45% higher than that of flagellin of the core.It is postulated that the high content of serine may be responsible for the stability of the flagellar hooks through the development of hydrogen bridges. It is also assumed that the high level of amino acids with OH-groups in the core flagellin causes the binding of the subunits of flagellar sheath.

     

The lipopolysaccharides (O-antigens) of Rhodopseudomonas viridis

The present paper deals with the isolation, and chemical and serological characterization of the O-antigens (lipopolysaccharides, LPS) of the photosynthetic gram-negative bacterium Rhodopseudomonas viridis. The LPS are extractable with hot phenol/water, but unlike the phenol-soluble LPS of the closely related species Rhodopseudomonas palustris, the R. viridis O-antigens are preferentially extracted into the water phase. A mixture of phenol/chloroform/petroleum ether (PCP-method) does not extract the R. viridis LPS. All R. viridis LPS investigated belong to the same chemotype, the polysaccharide moiety of these O-antigens being composed of 3-O-methyl-l-xylose, 3-O-methyl-d-mannose, d-mannose, d-galactose, d-glucose, in addition to 2-keto-3-deoxyoctonate (KDO), glucosamine, 6-deoxyglucosamine (quinovosamine) and galactosamine uronic acid. The R. viridis O-antigens are clearly distinguishable from the l-glycero-d-mannoheptose containing O-antigens of R. palustris by the lack of this sugar (and of any other heptose) in the R. viridis LPS. The lipid moiety (lipid A) of the R. viridis O-antigen can be split off from the LPS by mild acid hydrolysis. Like lipid A from R. palustris, it differs remarkably from the well known lipid A of Enterobacteriaceae, in that d-glucosamine is replaced by a recently identified 2.3-diamino-2.3-dideoxyhexose in the R. viridis and R. palustris lipid A. Unlike enteric lipid A the R. viridis lipid A is phosphate-free and includes as the only fatty acid β-C₁₄OH which is exclusively amide-linked. All R. viridis strains belong to the same serotype so far as investigated, as shown by passive hemagglutination with the isolated O-antigens and rabbit antisera against heat-killed cells.     

5-Hydroxytryptamin im Gehirn der Eidechse (Lacerta viridis und Lacerta muralis)

Zusammenfassung Mit Hilfe der Methode von Falck und Hillarp wurde die Verteilung von 5-Hydroxytryptamin im Zentralnervensystem von Lacerta viridis und muralis untersucht. Mikrospektrometrische Analysen zeigen, daß sich die Gelbfluoreszenz wie formaldehyd-kondensiertes 5-Hydroxytryptamin verhält; chemische Bestimmungen ergeben hohe Werte von 5-Hydroxytryptamin im Gehirn der Eidechsen (5,2–6,4 g/g). Kerngebiete des Zwischen-, Mittel und Vorderhirns, die überwiegend in somatosensible oder sensorische Bahnen eingeschaltet sind, werden von Endaufsplitterungen 5-hydroxytryptaminhaltiger Neurone erreicht. Es wird angenommen, daß das Ursprungsgebiet dieser Fasersysteme im Tegmentum liegt. Der Nucleus reticularis mesencephali enthält zahlreiche Nervenzellen, deren Perikaryen einen hohen Gehalt an 5-Hydroxytryptamin aufweisen.

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5-Hydroxytryptamine in the brain of Lacerta viridis and Lacerta muralis

Summary The distribution of 5-hydroxytryptamine in the central nervous system of the lizards Lacerta viridis and muralis was investigated with the fluorescence method of Falck and Hillarp. Microspectrometric analyses revealed that the yellow fluorescence had the characteristics of the fluorophore of 5-hydroxytryptamine and chemical determinations on whole brains demonstrated the presence of considerable quantities of 5-hydroxytryptamine (5,2–6,4 g/g). Nuclear areas of the mesencephalon, di and telencephalon, which are mainly intercalated in sensory pathways, receive terminal ramifications of 5-hydroxytryptaminecontaining neurons. These fibres are presumed to originate from cells situated in the tegmentum. The nucleus reticularis mesencephali is shown to contain numerous perikarya of nerve cells rich in 5-hydroxytryptamine.

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Mit dankenswerter Unterstützung durch die Deutsche Forschungsgemeinschaft und die Joachim Jungius-Gesellschaft zur Förderung der Wissenschaften, Hamburg.

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Supported by grants from the Swedish Natural Science Research Council/project no. 99-35, and the Swedish Medical Research Council/project no. B 68-12x-712-03B.     

Die Thylakoidstrukturen von Rhodopseudomonas spec.

Zusammenfassung Ein neues, intensiv grünes, phototrophes Bakterium wurde isoliert und seine Thylakoidstrukturen untersucht. Die Thylakoide liegen hier in Form hochgeordneter, kompakter Thylakoidstapel vor, deren Einzelthylakoide offenbar relativ fest untereinander verbunden sind. In jeder Zelle liegt ein Thylakoidstapel.Die Absorptionsspektren der Chromoproteide unterscheiden sich charakteristisch von denen anderer phototropher Bakterien. Das infrarote Hauptabsorptionsmaximum liegt bei 1020m. Die Hauptfraktion des Bacteriochlorophylls gehört zum Typ b. Das Bakterium zeigt in seiner Thylakoidstruktur und seiner Pigmentzusammensetzung keine Übereinstimmung mit den Thiorhodaceen, Athiorhodaceen und Chlorobacteriaceen. Die systematische Zuordnung dieses Bakteriums ist noch unsicher. Es soll vorläufig als Rhodopseudomonas spec. (Stamm F) bezeichnet werden.

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Summary A new intensively green coloured phototroph bacterium was isolated and its thylakoid-structures (chromatophores) were investigated. The single thylakoids are joint together to big and high ordered thylakoidstaples. Every cell has only one thylakoid-pile. The in vivo-absorptionspectrum of this Rhodopseudomonas strain is quite different from the spectrum of other phototroph bacteria. The positions of the main absorption-maxima are 400 and 1020m. The main fraction of the extracted and chromatographically purified bacteriochlorophyll belongs to the b-type after the nomenclature of A. Jensen. max. of this bacteriochlorophyll b are 371, 441, 588, 676 and 799m and the maxima of bacteriophaeophytin are 368, 399, 529, 685 and 778m. The classification of this organism needs further investigations.

     

Strong homology between the small subunit of ribulose-1,5-bisphosphate carboxylase/oxygenase of two species of Acetabularia and the occurrence of unusual codon usage

Summary The complete nucleotide sequence of the genes encoding the Rieske FeS, the cytochrome b and the cytochrome c ₁ subunits of the ubiquinol-cytochrome c ₂ oxidoreductase from the photosynthetic purple bacterium Rhodopseudomonas viridis, and the derived amino acid sequences are presented. These three genes, fbcF, fbcB and fbcC, are located at contiguous sites of the genome. The DNA-deduced amino acid sequences are compared with known primary structures of corresponding proteins from other purple photosynthetic bacteria, as well as mitochondria, cyanobacteria and chloroplasts.Abbreviations BSA bovine serum albumin - Rb Rhodobacter - Rps Rhodopseudomonas     

Zur Taxonomie von Rhodopseudomonas palustris

Zusammenfassung Eine Reihe von Rhodopseudomonas palustris-Stämmen aus verschiedenen Herkünften wurden vergleichend unter Verwendung folgender Merkmale untersucht: Substratverwertung, in vivo-Absorptionsspektrum und Serologie der O-Antigene. Die gegen 2 Stämme gerichteten Antiseren zeigen hohe Spezifität. Die Verwendbarkeit der serologischen Kreuzreaktion für taxonomische Untersuchungen bei photosynthetischen Bakterien wird diskutiert.

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On the taxonomy of Rhodopseudomonas palustris

Summary Strains of Rhodopseudomonas palustris isolated from different habitats were compared with respect to their taxonomic features. All strains grew very well on formiate, acetate, propionate, butyrate, aspartate, inositol, ethanol, fructose, and p-amino-benzoate, respectively, as single carbon source. Most of the strains were able to use benzoic acid or glucose, too. But alanine was not found to be a good substrate. The maxima of the bacteriochlorophyll in-vivo-absorption spectra were estimated to be 376, 589, 802–805, and 858–875 nm. The shift of the infrared peak in the different strains is loosely correlated with the change of the carotenoid in vivo spectrum, the maxima of which were measured to be 470–480 nm (shoulder) 495–505 nm, and 520–545 nm (shoulder). Antisera were prepared against the strains 1e5 and 11/1. It was demonstrated that these antisera were directed against the lipopolysaccharides (O-antigen) of these bacteria. The antigen of 1e5 does not cross react with the antigen of 11/1. Strain 1e5 is the only one of 17 strains tested which is sensitive to the bacteriophage Rp1. The antigen of this strain cross reacted only with the antigen of strain K1. In contrast, the antigen of strain 11/1 cross reacted in some degree with most of the tested strains of Rps. palustris. No or very weak cross reaction was observed between the antigens of Rps. palustris (1e5, 11/1) and Rps. capsulata, Rps. spheroides, or R. rubrum, respectively. In contrast to 11/1 only heat-killed cells of strain 1e5 were agglutinated by anti-1e5.

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Im Text verwendete Abkürzungen LPS Lipopolysaccharid - R Rhodospirillum - Rps. Rhodopseudomonas - i.m. intramuskulär - s.c. subcutan - i.v. intravenös     

Probing the structure of the core light-harvesting complex (LH1) of Rhodopseudomonas viridis by dissociation and reconstitution methodology

A subunit complex was formed from the core light-harvesting complex (LH1) of bacteriochlorophyll(BChl)-b-containing Rhodopseudomonas viridis. The addition of octyl glucoside to a carotenoid-depleted Rps. viridis membrane preparation resulted in a subunit complex absorbing at 895 nm, which could be quantitatively dissociated to free BChl b and then reassociated to the subunit. When carotenoid was added back, the subunit could be reassociated to LH1 with a 25% yield. Additionally, the Rps. viridis - and -polypeptides were isolated, purified, and then reconstituted with BChl b. They formed a subunit absorbing near 895 nm, similar to the subunit formed by titration of the carotenoid depleted membrane, but did not form an LH1-type complex at 1015 nm. The same results were obtained with the -polypeptide alone and BChl b. Isolated polypeptides were also tested for their interaction with BChl a. They formed subunit and LH1-type complexes similar to those formed using polypeptides isolated from BChl-a-containing bacteria but displayed 6–10 nm smaller red shifts in their long-wavelength absorption maxima. Thus, the larger red shift of BChl-b-containing Rps. viridis is not attributable solely to the protein structure. The -polypeptide of Rps. viridis differed from the other -polypeptides tested in that it could form an LH1-type complex with BChl a in the absence of the - and -polypeptides. It apparently contains the necessary information required to assemble into an LH1-type complex. When the -polypeptide was tested in reconstitution with BChl a and BChl b with the - and -polypeptides, it had no effect; its role remains undetermined.Abbreviations B820 the subunit form of the core light-harvesting complex in BChl-a-containing bacteria which has an absorption maximum at or near 820 nm - B875 the core light-harvesting complex of Rhodobacter sphaeroides which has an absorption maximum at 875 nm - B881 the core light-harvesting complex of wild-type Rhodospirillum rubrum which has an absorption maximum at 881 nm - B895 the subunit form of the core light-harvesting complex in Rps. viridis which has an absorption maximum near 888–895 nm - B1015 the core light-harvesting complex of Rps. viridis which has an absorption maximum at 1015 nm - CD circular dichroism - LH1 the core light-harvesting complex - OG n-octyl -d-glucopyranoside     

Der Geißelapparat von Rhodopseudomonas palustris

Zusammenfassung Rhodopseudomonas palustris Stamm 11/1 wirft bei Änderung der Umweltsfaktoren seine subpolar inserierende Geißel ab. Dieser Vorgang erfolgt auch während niedrigtouriger Zentrifugation. Die im Zentrifugenüberstand strukturell vollkommen erhaltenen Geißeln werden durch differentielle Zentrifugation angereichert und gereinigt.Durch Behandlung der Geißeln mit Aqua bidest. oder durch Einfrieren (-15° C) und Auftauen der in Aqua bidest. oder 0,05 M Trispuffer (pH 7,4) suspendierten Geißeln dissoziieren die Geißelfilamente, während die Geißelhaken strukturell erhalten bleiben. Auf diesen Eigenschaften basiert die Isolationsmethode der Geißelhaken.Ammonsulfatfällungen in Suspensionen dissoziierter Geißeln führen zur Aussalzung der protein-(flagellin-)haltigen Komponenten (1. Aqua bidest. lösliches, feinflockiges Präcipitat; 2. Aqua bidest. unlösliches, grobflockiges Material), während nach Zentrifugation das nichtproteinhaltige Geißelscheidenmaterial im Überstand verbleibt.Die scheidenhaltigen Geißeln von Rhodopseudomonas palustris enthalten nur eine einzige Proteinkomponente, das Flagellin, aus dem die core-Untereinheiten bestehen.

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The flagellar apparatus of Rhodopseudomonas palustris IV. Isolation of the flagellum and its parts

Summary Rhodopseudomonas palustris, strain 11/1, loses its flagellum when the environment is changed, f.e. during low speed centrifugation. The flagella which are well preserved in their structure are found in the supernatant of such centrifugation. They can be purified by differential centrifugation.By treatment of the flagella with distilled water or by freezing (-15°C) and thawing the flagellar filament is decomposed into subunits, whereas the flagellar hook does not become desintegrated. By using this procedure the flagellar hooks have been isolated.The solubilized flagellar filament material was precipitated by treatment with ammonium sulfate. Two different flagellin containing fractions were obtained, one is a fine precipitate which is soluble in distilled water, the other one is an unsoluble flocky material. After spinning down the protein containing fractions the nonproteinous sheath material remains in the supernatant.There is only one protein fraction in the total sheathed flagellum. This protein is the flagellin component of the core subunits.

     

Zum Vorkommen helixförmig angeordneter Ribosomen bei Rhodopseudomonas palustris

Zusammenfassung Es wird das Vorkommen von Polysomensäulen bei Rhodopseudomonas palustris beschrieben. An Hand der Daten ergab sich, daß diese Polysomen aus zwei helixförmig angeordneten Ribosomensträngen aufgebaut sind, die eine linksdrehende Schraube bilden. Der Querschnitt der Schraube zeigt hexagonale Anordnung der Ribosomen. Der Steigungswinkel der Helices beträgt 20⁰, der Gesamtdurchmesser der hexagonalen Polysomensäule beträgt 375 Å. Diese Polysomenart kommt lediglich in der begeißelten Polregion vor und ist dicht unter der Cytoplasmamembran lokalisiert. Die Polysomen stehen mit der Cytoplasmamembran in Kontakt. Ihre Längsachse läuft parallel zur Plasmamembran.

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The occurrence of helical arranged ribosomes of rhodopseudomonas palustris

Summary Helical arranged ribosomes were detected in the polar region of Rhodopseudomonas palustris cells. They are attached to the cytoplasmic membrane. The columnar polysomes are shaped of two helical strings of ribosomes, which are arranged around the axis of the screw. The vertical projection of the single ribosomes in one turn of the screw is a hexagon. The helices are left handed. The angle between the horizontal line and the ribosome chain in the helix is =20⁰. The diameter of the polyribosome column amounts to 375 Å.

     

Variable planar particle arrangements in the photosynthetic membrane of Rhodopseudomonas viridis

The thylakoids of Rhodopseudomonas viridis have been studied by freeze-fracturing whole cells. Depending on growth conditions and treatment before freezing, three different types of particle arrangements in the photosynthetic membrane are reported: a random arrangement, an isometric (quadratic) lattice arrangement with a lattice constant of 12.5 ± 0.8 nm, and a hexagonal lattice arrangement with a lattice constant of 12.5 ± 0.8 nm.     

Three-dimensional structures of photosynthetic reaction centers

In this article, the three-dimensional structures of photosynthetic reaction centers (RCs) are presented mainly on the basis of the X-ray crystal structures of the RCs from the purple bacteria Rhodopseudomonas (Rp.) viridis and Rhodobacter (Rb.) sphaeroides. In contrast to earlier comparisons and on the basis of the best-defined Rb. sphaeroides structure, a number of the reported differences between the structures cannot be confirmed. However, there are small conformational differences which might provide a basis for the explanation of observed spectral and functional discrepancies between the two species.A particular focus in this review is on the binding site of the secondary quinone (Q_B), where electron transfer is coupled to the uptake of protons from the cytoplasm. For the discussion of the Q_B site, a number of newlydetermined coordinate sets of Rp. viridis RCs modified at the Q_B site have been included. In addition, chains of ordered water molecules are found leading from the cytoplasm to the Q_B site in the best-defined structures of both Rp. viridis and Rb. sphaeroides RCs.Abbreviations B_A accessory bacteriochlorophyll in the active branch - B_B accessory bacteriochlorophyll in the inactive branch - D primary electron donor (special pair) - D_L special pair bacteriochorophyll bound by the L subunit - D_M special pair bacteriochorophyll bound by the M subunit - Q_A primary electron acceptor quinone - Q_B secondary electron acceptor quinone - RC reaction center - Rb. Rhodobacter - Rp. Rhodopseudomonas - _A bacteriopheophytin in the active branch - _B bacteriopheophytin in the inactive branch     

Photoheterotrophic utilization of acetate by the wild type and an acetate-adapted mutant of Rhodopseudomonas capsulata

Rhodopseudomonas capsulata strain St. Louis can grow anaerobically in the light-with acetate as the carbon source. The organism is sensitive to acetate, however, initial concentrations exceeding 25 mM resulting in an extensive growth lag. Bicarbonate is not required for growth of this strain on acetate, but addition of bicarbonate shortens the lag phase in media with high initial acetate concentration. A spontaneous mutant which exhibited a minimal lag phase and rapid growth rates on acetate media was derived from strain St. Louis. This mutant possessed elevated levels of the glyoxylate cycle enzyme, isocitrate lyase.     

Morphologie und Wirtskreis eines neu isolierten Rhodopseudomonas palustris-Phagen

Zusammenfassung Aus Teichwasser in der Nähe Freiburgs wurde ein Bacteriophage angereichert, der Rhodopseudomonas palustris, Stamm 1 e 5 befällt. Dieser, als Rp 1 bezeichnete Phage kann in anaeroben Lichtkulturen von Rps. palustris bis zu einem Titer von 10⁹ vermehrt werden. Der Infektionscyclus findet auch in aerober Dunkelkultur statt. Von 17 untersuchten Rps. palustris-Stämmen wird nur der Stamm 1 e 5 befallen und bei ihm die Entwicklung von Plaques beobachtet. Das Capsid des Phagen ist icosaedrisch. Die Capsomeren erscheinen pentagonal. Das Capsid hat einen Durchmesser von 380–390 . Die Festheftung des Phagen an der Oberfläche der Wirtszelle oder an den Thylakoiden erfolgt mit einer röhrenförmigen Struktur, die 200 lang und 55–60 dick ist.

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Morphology and host range of a new isolated Rhodopseudomonas palustris-phage

Summary A Phage active against Rhodopseudomonas palustris was isolated from freshwater ponds near Freiburg. The Phage is called Rp 1. Rp 1 could be propagated to titres of 10⁹ plaque-forming units/ml in anaerobic light cultures. It is also synthesized in aerobic dark cultures of Rps. palustris strain 1 e 5. The host range of this phage is very narrow. Only one of seventeen strains of Rps. palustris is able to propagate the phage. The other tested Athiorhodaceae do not give rise to plaque development. The Rp 1 virus consists of an icosahedral head (380–390 in diameter) and a tail like structure. After degradation of the capsid pentagonal capsomeres become visible. The phages are attached by a hollow tube (length 200 , diameter 55–60 ) to the host cell. In negative stained preparations of phages many Rp 1 are seen attached to the thylakoid of the bacteria.

     

Quantitative Bestimmung der Fettsäuren von Rhodospirillum rubrum und Rhodopseudomonas capsulata während der Thylakoidmorphogenese

Zusammenfassung Eine Methode zur quantitativen Bestimmung des Fettsäuregehaltes im Mikrogrammbereich wird angegeben und auf Spezifität untersucht. Thylakoide aus Rhodospirillum rubrum und Rhodopseudomonas capsulata enthalten 330 bzw. 350 g Fettsäuren/mg Protein und 16,1 bzw. 15,4 g Lipid-Phosphor/mg Protein. In aeroben Dunkelkulturen beider Organismen werden 100–120 g Fettsäuren und 3,0–4,3 g Lipid-Phosphor pro mg Protein gefunden. In Thylakoiden sind 15–20%, in ganzen Zellen 25–45% der Fettsäuren nicht in Phospholipiden vom Glycerintyp gebunden.Wird die Thylakoidsynthese durch Absenken des O₂-Partialdruckes induziert, steigt der Fettsäuregehalt um 30%, der Lipid-Phosphor-Gehalt um 40% an. Elektronenmikroskopische Aufnahmen lassen jedoch auf eine Verdopplung bis Verdreifachung des Gehaltes an Membranen schließen. Dieser Widerspruch wird mit der Annahme erklärt, daß Phospholipide in gramnegativen Bakterien nicht nur in Membranen, sondern auch in der Zellwand lokalisiert sind. Der Wert der Bestimmung des Lipid-Phosphor in ganzen Zellen gramnegativer Bakterien als Maß für den Membrangehalt wird diskutiert.

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Quantitative determinations of long-chain fatty acids in dark growing cells of Rhodospirillum rubrum and rhodopseudomonas capsulata during the synthesis of thylakoids

Summary The content of fatty acids in the thylakoids of Rhodospirillum rubrum and Rps. capsulata is 330 g and 350 g/mg protein, respectively, and the content of lipidphosphorus 16.1 and 15.4 g/mg protein, respectively. In aerobic dark cultures of both organisms 100 to 120 g fatty acids and 3.0 to 4.3 g lipid phosphorus per mg protein are demonstrable. 15 to 20% of fatty acids in thylakoids and 25 to 45% of fatty acids in whole cells are not bound to glycerol phosphatides. After induction of thylakoid synthesis by lowering of oxygen partial pressure the specific content of fatty acids is increased by 30% and the concentration of lipid phosphorus by 40%. Under the same conditions a two or threefold increase of membrane surface as evaluated from electron micrographs is observable. This pronounced difference is explainable by the assumption, that phospholipids in gram-negative bacteria are not only localized in membranes, but also in the cell wall. The validity of determinations of lipid phosphorus in whole cells of gram-negative bacteria as a measure for membrane content is discussed.

     

Characterization of an acetate-decarboxylating,non-hydrogen-oxidizing methane bacterium

A methanogenic bacterium, commonly seen in digested sludge and referred to as the fat rod or Methanobacterium soehngenii, has been enriched to a monoculture and is characterized. Cells are gramnegative, non-motile and appear as straight rods with flat ends. They form filaments which can grow to great lengths. The structure of the outer cell envelop is similar to Methanospirillum hungatii. The organism grows on a mineral salt medium with acetate as the only organic component. Acetate is the energy source, and methane is formed exclusively from the methyl group. Acetate and carbon dioxide act as sole carbon source and are assimilated in a molar ratio of about 1.9:1. The reducing equivalents necessary to build biomass from these two precursors are obtained from the total oxidation of some acetate. Hydrogen is not used for methane formation and is not needed for growth. Formate is cleaved into hydrogen and carbon dioxide. Coenzyme M was found to be present at levels of 0.35 nmol per mg of dry cells and F₄₂₀ amounted to 0.55 g per mg protein. The mean generation time was 9 days at 33°C.