Isolation and characterization of a rubredoxin and two ferredoxins from Desulfovibrio africanus

Rubredoxin and two distinct ferredoxins have been purified from Desulfovibrio africanus. The rubredoxin has a molecular weight of 6000 while the ferredoxins appear to be dimers of identical subunits of approximately 6000 to 7000 molecular weight. Rubredoxin contains one iron atom, no acid-labile sulfide and four cysteine residues per molecule. Its absorbance ratio A278/A490 is 2.23 and its amino acid composition is characterized by the absence of leucine and a preponderance of acidic amino acids. The two ferredoxins, designated I and II, are readily separated on DEAE-cellulose. The amino acid compositions of ferredoxins I and II show them to be different protein species; the greater number of acidic amino acid residues in ferredoxin I than in ferredoxin II appears to account for separation based on electronic charge. Both ferredoxins contain four iron atoms, four acid-labile residues per molecule. Spectra of the two ferredoxins differ from those of ferredoxins of other Desulfovibrio species by exhibiting a pronounced absorption peak at 283 nm consistent with an unusual high content of aromatic residues. The A385/A283 absorbance ratio of ferredoxins I and II are 0.56 and 0.62, respectively. The N-terminal sequencing data of the two ferredoxins clearly indicate that ferredoxins I and II are different protein species. However, the two proteins exhibit a high degree of homology.     

Isolation and characterization of a rubredoxin and two ferredoxins from Desulfovibrio africanus

Rubredoxin and two distinct ferredoxins have been purified from Desulfovibrio africanus. The rubredoxin has a molecular weight of 6000 while the ferredoxins appear to be dimers of identical subunits of approximately 6000 to 7000 molecular weight. Rubredoxin contains one iron atom, no acid-labile sulfide and four cysteine residues per molecule. Its absorbance ratio A₂₇₈/A₄₉₀ is 2.23 and its amino acid composition is characterized by the absence of leucine and a preponderance of acidic amino acids.

The two ferredoxins, designated I and II, are readily separated on DEAE-cellulose. The amino acid compositions of ferredoxins I and II show them to be different protein species; the greater number of acidic amino acid residues in ferredoxin I than in ferredoxin II appears to account for separation based on electronic charge. Both ferredoxins contain four iron atoms, four acid-labile sulfur groups and either four (ferredoxin II) or six (ferredoxin I) cysteine residues per molecule. Spectra of the two ferredoxins differ from those of ferredoxins of other Desulfovibrio species by exhibiting a pronounced absorption peak at 283 nm consistent with an unusual high content of aromatic residues. The A₃₈₅/A₂₈₃ absorbance ratio of ferredoxins I and II are 0.56 and 0.62, respectively.

The N-terminal sequencing data of the two ferredoxins clearly indicate that ferredoxins I and II are different protein species. However, the two proteins exhibit a high degree of homology.

The physiological activity of ferredoxins I and II appears to be similar as far as the electron transfer in the phosphoroclastic reaction is concerned.     

Isolation and properties of crystalline ferredoxin from lactuca sativa

Lettuce ferredoxin has been purified to homogeneity, with a yield of 18 mg/kg of denerved leaves. It crystallizes in magnificent needles, often clustered in broom-like sheaves. The absorption spectrum showed maxima at 460, 422, 330 and 274 nm,with a ratio A₄₂₂/A₂₇₄, of 0.46. The mM absorption coefficient was 9.74 at 422 nm, and 21.62 at 274 nm. This ferredoxin showed a pI = 4.7 and an E′₀ = ?425 mV (at pH = 7.7). MWs of 12 400, 11480 and 13000 were obtained by sucrose gradient centrifugation, and on the basis of the amino acid composition and the iron content, respectively, with an average of 12 300. The amino acid analysis showed the existence of one methionine residue per mole, with 105 amino acid residues. There are two iron atoms and two labile sulfide groups per mole; 4 half-cystine residues were found by performic acid oxidation, and 5 cysteine groups when determined by titration with pHMB. The native protein is not fixed on thiol-Sepharose 4B, but it is quantitatively retained after incubation with 8 M urea. Lettuce ferredoxin showed a 62, 58 and 78% effectiveness with the spinach ferredoxin-NADP reductase, nitrite reductase and fructose-1,6-diphosphatase (FDPase), respectively, when compared with the spinach ferredoxin. This different behaviour of both ferredoxins is joined to genetic-structural relationships, and suggests that the role of ferredoxin in FDPase activation is more sophisticated than that of a mere nonspecific reductant.     

The amino acid sequence of ferredoxin from Triticum aestivum (wheat).

The amino acid sequence of the ferredoxin of Triticum aestivum (wheat) was determined by using a Beckman 890C sequencer in combination with the dansyl--phenylisothiocyanate method to characterize peptides obtained by tryptic, chymotryptic and thermolytic digestion of CNBr-cleavage fragments. The molecule consists of a single polypeptide chain of 97 residues and has an unblocked N-terminus. It shows considerable similarity to other plant-type ferredoxins.     

Relationship Between the Sequence and Function of Rubisco rbcL in Nucleo-Cytoplasmic Hybrid Wheat

Nucleo-cytoplasmic hybrid wheat NC4 is resistent to a number of stresses and produces high yield. It was obtained by crossing Aegilops squarrosa (♀) with Triticum aestivum ( ♂ ), and several back crossings. The rbcLs (the gene of large subunit of Rubisco ( rihulose-1, 5-bisphosphate carboxylase/oxygenase )) cloned from NC4 and T. aestivum have been sequenced, and the result showed that the rbcL of NC4 was originated from Ae. squarrosa. The ratio of carhoxylase activity to oxygenase activity, Vco2/Vo2, of hybrid NC4 Was lower than that of Ae. squarrosa, but higher than that of T. aestivum. This difference may be accounted for the higher yield of NC4 than that of T. aestivum. Sequence analysis showed that three nucleotides in the rbcL of NC4 which were different from those of T. aestivum, corresponded to the No. 14, 86 and 95 amino acid residues of rbcL.     

Purification and characterization of a highly acidic 2Fe-ferredoxin from Halobacterium of the dead sea

A 2Fe-ferredoxin from Halobacterium of the Dead Sea has been purified by chromatography on Sepharose and DEAE-cellulose, using decreasing concentration gradients of ammonium sulfate. Its amino acid composition reveals an extremely high excess of acidic amino acid residues: 44 glutamate and aspartate residues (of which 4 are in the amide form), compared to 6 lysines and arginines, as well as a high content of aromatic amino acids. The molecular weight of this ferredoxin was found to be 14,000 by amino acid composition, sedimentation equilibrium, and iron content. The millimolar coefficients at the maxima of the visible absorption spectrum are: 28.0 (277 nm), 12.2 (330 nm), 9.1 (420 nm), and 8.3 (465 nm). The optical properties—absorption and CD spectra in the visible region—of this ferredoxin are very similar to those of plant and algal ferredoxins, whereas its redox potential is much higher: ?345 ± 5 mV (at pH 7.3, 0.5 m NaCl). Although it is reduced by illuminated chloroplasts, it cannot mediate the photoreduction of NADP in their presence. Data reported elsewhere suggest that its physiological function might be to serve as an electron donor for nitrite reduction.     

Isolation and properties of a ferredoxin from leaves of Sambucus racemosa L.

Ferredoxin was isolated in good yield from leaves of Sambucus racemosa L. by the following procedure: (1) homogenization in buffered acetone-water (1:1v/v); (2) ion-exchange chromatography on several columns of DEAE-cellulose; and (3) purification by gel filtration with Sephadex G-75. The ultraviolet and visible spectrum showed maxima at 277, 331, 423, and 466 nm. The electron paramagnetic resonance spectrum was centered around g = 1.957. The protein sustained an initial photoreduction rate of 86 mumol NADP per milligram chlorophyll per hour. The amino acid composition was found to be Lys 5, His 2, Arg1, Asx11, Thr5, Ser7, Glx17, Pro6, Gly7, Ala6-7, Cys4, Val8, Ile5, Leu7, Tyr3, Phe2, and Trp1. The molecule had a molecular weight of 10 700 and contained two atoms of iron. The amino-terminal residue was alanine. These properties are highly similar to those of other angiosperm ferredoxins. Sambucus ferredoxin was found to be most closely related to that of Leucaena.     

Molecular cloning and nucleotide sequences of bovine hepato-ferredoxin cDNA; identical primary structures of hepato- and adreno-ferredoxins.

1. The ferredoxin from bovine liver mitochondria, so-called hepatoredoxin, was purified and characterized as to its molecular weight, optical absorption spectrum and amino acid composition. 2. These properties were found to be very similar to those of adreno-ferredoxin. 3. To clarify the molecular basis of tissue specificity, the ferredoxin clones were obtained from a bovine liver library and the cDNA sequence of hepato-ferredoxin was determined. 4. The nucleotide sequence of hepato-ferredoxin clone was found to be identical to that of adreno-ferredoxin clone except for a single nucleotide in the 3' non-translated region. 5. Identical amino acid sequence of the two ferredoxins was confirmed by determining the partial amino acid sequence of the purified hepato-ferredoxin. 6. The results indicated that the organ specific activity of purified ferredoxin could not be explained by the different primary structure nor different RNA processing. 7. Other factors may be involved in the tissue specific properties of ferredoxins.     

Complete amino acid sequence of ferredoxin from Peridinium bipes (Dinophyceae)

The amino acid sequence of the major ferredoxin component isolated from a dinoflagellate, Peridinium bipes, was completely determined. Staphylococcus aureus V8 proteolytic, tryptic and chymotryptic peptides of Cm-ferredoxin were prepared and sequenced. The sequence was Phe-Lys-Val-Thr-Leu-Asp-Thr-Pro-Asp-Gly-Lys-Lys-Ser-Phe-Glu-Cys- Pro-Gly-Asp-Ser-Tyr-Ile-Leu-Asp-Lys-Ala-Glu-Glu-Glu-Gly-Leu-Glu-Leu-Pro- Tyr-Ser - Cys-Arg-Ala-Gly-Ser-Cys-Ser-Ser-Cys-Ala-Gly-Lys-Val-Leu-Thr-Gly-Ser-Ile- Asp-Gln - Ser-Asp-Gln-Ala-Phe-Leu-Asp-Asp-Asp-Gln-Gly-Gly-Asp-Gly-Tyr-Cys-Leu-Thr- Cys-Val - Thr-Tyr-Pro-Thr-Ser-Asp-Val-Thr-Ile-Lys-Thr-His-Cys-Glu-Ser-Glu-Leu. It was composed of 93 amino acid residues with 7 cysteine residues, the highest number found among the chloroplast-type ferredoxins so far sequenced. A cysteine residue was found for the first time at the 89th position in a chloroplast-type ferredoxin. Calculation of the numbers of amino acid differences among chloroplast-type ferredoxins indicates that the Peridinium ferredoxin is far divergent not only from higher plant ferredoxins but also from blue-green algal ferredoxins.     

Discovery and mapping of wheat Ph1 suppressors

Pairing between wheat (Triticum turgidum and T. aestivum) homeologous chromosomes is prevented by the expression of the Ph1 locus on the long arm of chromosome 5B. The genome of Aegilops speltoides suppresses Ph1 expression in wheat x Ae. speltoides hybrids. Suppressors with major effects were mapped as Mendelian loci on the long arms of Ae. speltoides chromosomes 3S and 7S. The chromosome 3S locus was designated Su1-Ph1 and the chromosome 7S locus was designated Su2-Ph1. A QTL with a minor effect was mapped on the short arm of chromosome 5S and was designated QPh.ucd-5S. The expression of Su1-Ph1 and Su2-Ph1 increased homeologous chromosome pairing in T. aestivum x Ae. speltoides hybrids by 8.4 and 5.8 chiasmata/cell, respectively. Su1-Ph1 was completely epistatic to Su2-Ph1, and the two genes acting together increased homeologous chromosome pairing in T. aestivum x Ae. speltoides hybrids to the same level as Su1-Ph1 acting alone. QPh.ucd-5S expression increased homeologous chromosome pairing by 1.6 chiasmata/cell in T. aestivum x Ae. speltoides hybrids and was additive to the expression of Su2-Ph1. It is hypothesized that the products of Su1-Ph1 and Su2-Ph1 affect pairing between homeologous chromosomes by regulating the expression of Ph1 but the product of QPh.ucd-5S may primarily regulate recombination between homologous chromosomes.     

The amino acid sequence of ferredoxin from Sambucus nigra

The amino acid sequence of the ferredoxin from Sambucus nigra consists of a single polypeptide chain of 97 amino acid residues, 5 of which are cysteine. The positions of the 4 cysteine residues which bind the iron atoms of the active centre are identical to those of other ferredoxins. Due to difficulties of obtaining pure protein, residues 87–90 have only been identified from the amino acid analysis of peptide C 10 and by homology with other higher plant ferredoxins.     

Ferredoxin and Formyltetrahydrofolate Synthetase: Comparative Studies with Clostridium acidiurici, Clostridium cylindrosporum, and Newly Isolated Anaerobic Uric Acid-Fermenting Strains

Six strains of Clostridium acidiurici and three strains of C. cylindrosporum were isolated from soil samples by enrichment culture with uric acid as the source of carbon, nitrogen, and energy. The newly isolated strains were characterized by their spore morphology and the amounts of glycine and formate formed by the fermentation of uric acid. The strains were easily identified as belonging to one species or the other on the basis of spore morphology and formate production. The crystal properties and spectra of the native ferredoxins of all the strains isolated and the amino acid composition and partial carboxy-terminal sequence of all their apoferredoxins were determined. All the ferredoxins were tested for cross-reactivity with antiserum to C. acidiurici ferredoxin by microcomplement fixation. Five of the six C. acidiurici strains, which had ferredoxins with amino acid compositions identical to that from C. acidiurici, also showed immunological identity (immunological distance = 0.0). These results suggest sequence identity. The one strain with a different amino acid composition failed to show complete cross-reactivity. Two of the three C. cylindrosporum strains have ferredoxin amino acid compositions identical to that from C. cylindrosporum. The third strain had a minimum of five differences in sequence. All C. cylindrosporum strains had ferredoxins that differed considerably from C. acidiurici strains (minimum of eight to nine differences), and none of these ferredoxins cross-reacted with antisera to C. acidiurici ferredoxin. Antisera were prepared to formyltetrahydrofolate synthetase from C. acidiurici and C. cylindrosporum, and all possible comparisons were made by using immunodiffusion and microcomplement fixation. There is more intraspecies variation in the synthetases than in the ferredoxins; however, the results suggest considerable interspecies differences in both proteins. These results suggest a low degree of genomic relatedness between the two species, which contrasts sharply with their apparent high degree of phenotypic similarity.     

Purification and molecular properties of a soluble ferredoxin from Rhodopseudomonas capsulata

A soluble ferredoxin was purified from the photosynthetic bacterium Rhodopseudomonas capsulata and characterized. Unlike Rhodospirillum rubrum, where two soluble ferredoxins have been found, only a single species was found in Rps. capsulata. The amino acid composition, ultraviolet-visible spectral properties, molecular weight (12000) and biological activity were determined. The ultraviolet-visible spectrum is similar to that of other bacterial ferredoxins, with a maximum when oxidized at 380 nm (? = 26.1 · 10³ M^-1 · cm^-1). The possible roles of this ferredoxin in the cellular metabolism are discussed.     

Comparative studies on two ferredoxins from the cyanobacterium Nostoc strain MAC.

Two ferredoxins were isolated from the cyanobacterium Nostoc strain MAC grown autotrophically in the light or heterotrophically in the dark. In either case approximately three times as much ferredoxin I as ferredoxin II was obtained. Both ferredoxins had absorption maxima at 276, 282 (shoulder), 330, 423 and 465 nm in the oxidized state, and each possessed a single 2 Fe-2S active centre. Their isoelectric points were approx. 3.2. The midpoint redox potentials of the ferredoxins differed markedly; that of ferredoxin I was --350mV and that of ferredoxin II was --445mV, at pH 8.0. The midpoint potential of ferredoxin II was unusual in being pH dependent. Ferredoxin I was most active in supporting NADP+ photoreduction by chloroplasts, whereas ferredoxin II was somewhat more active in pyruvate decarboxylation by the phosphoroclastic system of Clostridum pasteurianum. Though the molecular weights of the ferredoxins determined by ultracentrifugation were the same within experimetnal error, the amino acid compositions showed marked differences. The N-terminal amino acid sequences of ferredoxins I and II were determined by means of an automatic sequencer. There are 11--12 differences between the sequences of the first 32 residues. It appears that the two ferredoxins have evolved separately to fulfil different roles in the organism.     

牡山羊草Aegilops juvenalis Puroindoline b基因的克隆

Puroindoline a（Pina）和puroindoline b（Pinb）是控制小麦籽粒硬度的主效基因。根据已报道的小麦Pinb基因的保守序列,设计合成了一对特异性引物,对六倍体牡山羊草Aegilops juvenalis（UUMMDD）的基因组DNA和胚乳eDNA进行Pinb基因扩增、克隆和序列测定,发现了两个新型Pinb等位基因Pinb-allele-1和Pinb-allele-2。该基因全长360bp,编码119个氨基酸残基。它编码的蛋白和麦类作物Puroindoline B（PinB）的成熟蛋白有非常高的同源性,具有麦类作物PinB蛋白所特有的WPTKWWK的色氨酸结构域和10个半胱氨酸所形成的5个二硫键结构。与软粒小麦ev．Capitole的Pinb-D1a相比较,其核苷酸同源性为93．1％、93．3％,氨基酸同源性为90．8％、92．4％。Pinb。allele。1和Pinb—allele一2分别含有11和9个氨基酸变异位点。RT—PCR证实了Pinb—allele一2基因在籽粒胚乳中的表达。SouthernBlot分析结果表明,牡山羊草中含有两个拷贝的Pinb基因,其中包含着与小麦差异较大的籽粒硬度控制基因。     

Two distinct ferredoxins from Rhodobacter capsulatus: complete amino acid sequences and molecular evolution

Two distinct ferredoxins were purified from Rhodobacter capsulatus SB1003. Their complete amino acid sequences were determined by a combination of protease digestion, BrCN cleavage and Edman degradation. Ferredoxins I and II were composed of 64 and 111 amino acids, respectively, with molecular weights of 6,728 and 12,549 excluding iron and sulfur atoms. Both contained two Cys clusters in their amino acid sequences. The first cluster of ferredoxin I and the second cluster of ferredoxin II had a sequence, CxxCxxCxxxCP, in common with the ferredoxins found in Clostridia. The second cluster of ferredoxin I had a sequence, CxxCxxxxxxxxCxxxCM, with extra amino acids between the second and third Cys, which has been reported for other photosynthetic bacterial ferredoxins and putative ferredoxins (nif-gene products) from nitrogen-fixing bacteria, and with a unique occurrence of Met. The first cluster of ferredoxin II had a CxxCxxxxCxxxCP sequence, with two additional amino acids between the second and third Cys, a characteristics feature of Azotobacter-[3Fe-4S] [4Fe-4S]-ferredoxin. Ferredoxin II was also similar to Azotobacter-type ferredoxins with an extended carboxyl (C-) terminal sequence compared to the common Clostridium-type. The evolutionary relationship of the two together with a putative one recently found to be encoded in nifENXQ region in this bacterium [Moreno-Vivian et al. (1989) J. Bacteriol. 171, 2591-2598] is discussed.     

Amino acid sequence of [2Fe-2S] ferredoxin from Clostridium pasteurianum

The complete amino acid sequence of the [2Fe-2S] ferredoxin from the saccharolytic anaerobe Clostridium pasteurianum has been determined by automated Edman degradation of the whole protein and of peptides obtained by tryptic and by staphylococcal protease digestion. The polypeptide chain consists of 102 amino acids, including 5 cysteine residues in positions 11, 14, 24, 56, and 60. The sequence has been analyzed for hydrophilicity and for secondary structure predictions. In its native state the protein is a dimer, each subunit containing one [2Fe-2S] cluster, and it has a molecular weight of 23,174, including the four iron and inorganic sulfur atoms. The extinction coefficient of the native protein is 19,400 M-1 cm-1 at 463 nm. The positions of the cysteine residues, four of which are most probably the ligands of the [2Fe-2S] cluster, on the polypeptide chain of this protein are very different from those found in other [2Fe-2S] proteins, and in other ferredoxins in general. In addition, whole sequence comparisons of the [2Fe-2S] ferredoxin from C. pasteurianum with a number of other ferredoxins did not reveal any significant homologies. The likely occurrence of several phylogenetically unrelated ferredoxin families is discussed in the light of these observations.     

Ferredoxin from a red alga, Porphyra umbilicalis.

A plant-algal type ferredoxin was isolated from the red alga, Porphyra umbilicalis. In its oxidised form the ferredoxin had absorption maxima at 277, (281), 323, 420 and 462 nm. Two atoms each of non-haem iron and labile sulphur were present per molecule protein. The midpoint potential of the protein was -400 mV and it effectively mediated electron transport in the NADP-photoreduction system of barley. The amino acid composition of Porphyra umbilicalis ferredoxin was determined as (Lys4, His2, Arg1, Asx10, Thr8, Ser7, Glx16-17, Pro3, Gly7, Ala8, Cys5, Val6, Met1, Ile5, Leu8, Tyr5, Phe2). The minimum molecular weight of approximately 11000 was confirmed by sedimentation-equilibrium studies in the analytical ultracentrifuge. Approaching half of the total amino acid sequence was determined by means of an automatic sequencer.     

Isolation and properties of a ferredoxin from Anabaena Flos-Aquae

Ferredoxin was isolated from the blue-green alga Anabaena flos-aquae. Its homogeneity was shown by conventional and SDS-polyacrylamide gel electrophoresis, and isoelectric focusing on polyacrylamide gel columns, the latter indicating a pI at ca pH 3·7. The absorption spectrum had, in the oxidized state, maxima at 462, 421, 327 and 276 nm, with a shoulder at 284 nm, a spectrum characteristic of plant-type ferredoxins. The 421 : 276 nm absorbance ratio was typically 0.49. The ferredoxin effectively mediated the photoreduction of NADP⁺ by barley chloroplasts depleted of native ferredoxin. The MW obtained by sedimentation-equilibrium and sedimentation velocity-diffusion coefficient studies was ca 12 000 daltons, a value somewhat higher than suggested by amino acid composition data. The ferredoxin contained 2Fe and 2S per molecule.     

Purification and some properties of a 2Fe ferredoxin in Pseudomonas ovalis

A [2Fe-2S] ferredoxin was found in Pseudomonas ovalis which was grown in a medium supplemented with glucose and ammonium sulfate. The molecular weight of the 2Fe ferredoxin was estimated to be 13,000. It contained 2.2 gramatoms of non-heme iron and 2.3 gramatoms of acid-labile sulfur per mole protein. The absorption and circular dichroism spectra were characteristic of those of [2Fe-2S] type ferredoxins, especially adrenodoxin and putidaredoxin. The electron paramagnetic resonance spectrum of the reduced protein showed an axial symmetry (g = 2.020, g = 1.939). The amino acid composition was determined.