排序方式: 共有56条查询结果,搜索用时 15 毫秒
41.
Photosynthetic Electron Transport Involved in PxcA-Dependent Proton Extrusion in Synechocystis sp. Strain PCC6803: Effect of pxcA Inactivation on CO2, HCO3−, and NO3− Uptake
下载免费PDF全文
![点击此处可从《Journal of bacteriology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Masatoshi Sonoda Hirokazu Katoh Wim Vermaas George Schmetterer Teruo Ogawa 《Journal of bacteriology》1998,180(15):3799-3803
The product of pxcA (formerly known as cotA) is involved in light-induced Na+-dependent proton extrusion. In the presence of 2,5-dimethyl-p-benzoquinone, net proton extrusion by Synechocystis sp. strain PCC6803 ceased after 1 min of illumination and a postillumination influx of protons was observed, suggesting that the PxcA-dependent, light-dependent proton extrusion equilibrates with a light-independent influx of protons. A photosystem I (PS I) deletion mutant extruded a large number of protons in the light. Thus, PS II-dependent electron transfer and proton translocation are major factors in light-driven proton extrusion, presumably mediated by ATP synthesis. Inhibition of CO2 fixation by glyceraldehyde in a cytochrome c oxidase (COX) deletion mutant strongly inhibited the proton extrusion. Leakage of PS II-generated electrons to oxygen via COX appears to be required for proton extrusion when CO2 fixation is inhibited. At pH 8.0, NO3− uptake activity was very low in the pxcA mutant at low [Na+] (~100 μM). At pH 6.5, the pxcA strain did not take up CO2 or NO3− at low [Na+] and showed very low CO2 uptake activity even at 15 mM Na+. A possible role of PxcA-dependent proton exchange in charge and pH homeostasis during uptake of CO2, HCO3−, and NO3− is discussed. 相似文献
42.
G. A. Peschek G. Schmetterer G. Lauritsch W. H. Nitschmann P. F. Kienzl R. Muchl 《Archives of microbiology》1982,131(3):261-265
The cytochrome content of membranes isolated from seven species of cyanobacteria was investigated in terms of conventional difference spectra, carbon monoxide difference spectra, photoaction spectra and photodissociation spectra, and by extraction of acid-labile heme followed by spectral identification. In addition, the effect of various inhibitors and activators on the oxidation of horse heart cytochrome c by the membrane was studied. Both the spectral features and the properties of the cytochrome oxidase reaction catalysed by the membranes suggested the presence of a terminal oxidase strikingly similar to mitochondrial ferrocytochrome c: oxygen oxidoreductase (EC. 1.9.3.1).Abbreviations PMS
phenazine methosulfate
- TMPD
N,N,N,N-tetramethyl-p-phenylenediamine
- Cyt
cytochrome 相似文献
43.
Georg R. Schmetterer 《Plant molecular biology》1990,14(5):697-706
Synechocystis sp. PCC 6803 is capable of facultative photoheterotrophy with glucose as the sole carbon source. Eight mutants that were unable to take up glucose were transformed with plasmids from pooled gene banks of wild-type Synechocystis DNA prepared in an Escherichia coli vector that does not replicate in Synechocystis. One mutant (EG216) could be complemented with all gene banks to restore ability for photoheterotrophic growth. One of the gene banks was fractionated into single clones and plasmid DNA from each clone used to complement EG216. This yielded a 1.5 kb DNA fragment that was sequenced. It contained one complete open reading frame (gtr) whose putative gene product displayed high sequence conservation with the xylose transporter of E. coli and the mammalian glucose transporters. Further, the isolated gtr gene interrupted in vitro by a kanamycin resistance cassette could be used to construct mutants from wild-type Synechocystis sp. PCC 6803 that lacked a functional glucose transporter, thus confirming the identity of the gtr gene with the glucose transporter gene. This is the first prokaryotic glucose transporter known to share a sequence relationship with mammalian glucose transporters and the first sugar transporter from a cyanobacterium characterized at the sequence level. 相似文献
44.
Electron-transport activities supported by seven different electron donor/acceptor couples in the light and in the dark, respectively, were measured in particle preparations of the cyanobacterium (blue-green alga) Anacystis nidulans after growth at 40, 30 and 25°C. The Arrhenius plots of the photosynthetic electron-transport reactions between ascorbate (plus 2,6-dichlorophenolindophenol (DCIP)) and NADP+, diphenylcarbazide and DCIP, diaminodurene and benzyl viologen (O2), and the plot of the photooxidation of reduced horse heart cytochrome c showed a single discontinuity at approx. 24–25, 15–17 and 10–13°C in membranes derived from cells grown at 40, 30 and 25°C, respectively. By contrast, the dark respiratory electron-transport reactions between NADPH, ascorbate (plus DCIP) or reduced horse heart cytochrome c and oxygen, and the reduction by horse heart cytochrome c of the aa3-type terminal oxidase as followed directly by dual-wavelength spectrophotometry, all gave Arrhenius plots distinguished by two distinct breaks: The break at the higher temperature corresponded to the break also found in the Arrhenius plots of the photosynthetic reactions while an additional discontinuity was observed at 17–18, 8–9 and 5–6°C in membranes prepared from cells grown at 40, 30 and 25°C, respectively. The temperatures at which the discontinuities in the Arrhenius plots occurred depended on the temperature at which the cells had been grown; they were independent, however, of the specific electron donors and acceptors employed. The characteristic features in the Arrhenius plots of respiratory and photosynthetic electron-transport reactions are discussed in terms of lipid-phase transitions in the cytoplasmic and the intracytoplasmic (thylakoid) membranes of A. nidulans. Implications for possibly distinct sites of the respiratory and photosynthetic electron-transport systems in A. nidulans will be mentioned. 相似文献
45.
46.
R. M. Werkmeister A. Popa Cherecheanu G. Garhofer D. Schmidl L. Schmetterer 《Cell and tissue research》2013,353(2):261-268
Imaging has gained a key role in modern glaucoma management. Traditionally, interest was directed toward the appearance of the optic nerve head and the retinal nerve fiber layer. With the improvement of the resolution of optical coherence tomography, the ganglion cell complex has also become routinely accessible in the clinic. Further advances have been made in understanding the structure-function relationship in glaucoma. Nevertheless, direct imaging of the retinal ganglion cells in glaucoma would be advantageous. With the currently used techniques, this goal cannot be achieved, because the transversal resolution is limited by aberrations of the eye. The use of adaptive optics has significantly improved transversal resolution, and the imaging of several cell types including cones and astrocytes has become possible. Imaging of retinal ganglion cells, however, still remains a problem, because of the transparency of these cells. However, the visualization of retinal ganglion cells and their dendrites has been achieved in animal models. Furthermore, attempts have been made to visualize the apoptosis of retinal ganglion cells in vivo. Implementation of these techniques in clinical practice will probably improve glaucoma care and facilitate the development of neuroprotective strategies. 相似文献
47.
An oligonucleotide directed against a highly conserved region of aa3-type cytochrome c oxidases was used to clone the cox genes from the cyanobacterium Synechocystis sp. PCC6803. Several overlapping clones were obtained that contained the coxB, coxA, and coxC genes, transcribed in the same direction in that order, coding for subunits II, I, and III, respectively. The deduced protein sequences of the three subunits showed high sequence similarity with the corresponding subunits of all known aa3-type cytochrome c oxidases. A 1.94-kb HindII fragment containing most of coxA and about half of coxC was deleted and replaced by a cassette coding for kanamycin resistance. Mutant cells that were homozygous for the deleted cox locus were obtained. They were viable under photoautotrophic and photoheterotrophic conditions, but contained no cytochrome c oxidase activity. Nevertheless, these mutant cells showed almost normal respiration, defined as cyanide-inhibitable O2 uptake by whole cells in the dark. It is concluded, therefore, that aa3-type cytochrome c oxidase is not the only terminal respiratory oxidase in Synechocystis sp. PCC6803.Abbreviations CM
cytoplasmic membrane
- DCMU
3-(3,4-dichlorophenyl)-1,1-dimethylurea
- HQNO
2-heptyl-4-hydroxyquinoline N-oxide
- ICM
intracytoplasmic membranes
- SU
subunit
- TES
(N-tris(hydroxymethyl)methyl)-2-aminoethane sulfonic acid 相似文献
48.
Partial 18S rRNA sequences of five chelicerate arthropods plus a
crustacean, myriapod, insect, chordate, echinoderm, annelid, and
platyhelminth were compared. The sequence data were used to infer phylogeny
by using a maximum-parsimony method, an evolutionary-distance method, and
the evolutionary-parsimony method. The phylogenetic inferences generated by
maximum-parsimony and distance methods support both monophyly of the
Arthropoda and monophyly of the Chelicerata within the Arthropoda. These
results are congruent with phylogenies based on rigorous cladistic analyses
of morphological characters. Results support the inclusion of the
Arthropoda within a spiralian or protostome coelomate clade that is the
sister group of a deuterostome clade, refuting the hypothesis that the
arthropods represent the "primitive" sister group of a protostome coelomate
clade. Bootstrap analyses and consideration of all trees within 1% of the
length of the most parsimonious tree suggest that relationships between the
nonchelicerate arthropods and relationships within the chelicerate clade
cannot be reliably inferred with the partial 18S rRNA sequence data. With
the evolutionary-parsimony method, support for monophyly of the Arthropoda
is found in the majority of the combinations analyzed if the coelomates are
used as "outgroups." Monophyly of the Chelicerata is supported in most
combinations assessed. Our analyses also indicate that the
evolutionary-parsimony method, like distance and parsimony, may be biased
by taxa with long branches. We suggest that a previous study's inference of
the Arthropoda as paraphyletic may be the result of (a) having two few
arthropod taxa available for analysis and (b) including long-branched taxa.
相似文献
49.
Ludwig A Heimbucher T Gregor W Czerny T Schmetterer G 《Applied microbiology and biotechnology》2008,78(4):729-735
The unicellular cyanobacterium Synechocystis sp. PCC6714 can grow not only under photoautotrophic conditions, but also under chemoheterotrophic conditions if glucose
is added to the medium. This makes it useful for the study of many aspects of bioenergetic mechanisms. In contrast to its
closely related strain Synechocystis sp. PCC6803, which cannot grow chemoheterotrophically, Synechocystis PCC6714 is not naturally transformable. To enable gene transfer in this strain, we established a method for the introduction
of self-replicating IncQ plasmids and for gene replacement using electroporation.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
50.
We investigated the protective effect of vitamin D against liver damage caused by carbon tetrachloride (CCl4). Twenty-four male rats were divided into four equal groups: G1, untreated controls; G2, administered CCl4; G3, administered both CCl4 and vitamin D for 10 weeks; G4, administered CCl4 for 10 weeks and vitamin D for 12 weeks. At the end of experiment, intracardiac blood samples were taken and liver samples were removed. Hepatic damage due to CCl4 was assessed using biochemistry and histopathology. Glutathione (GSH) levels decreased, while malondialdehyde (MDA) levels increased in liver tissues of G2. Alanine transaminase (ALT), alkaline phosphatase (ALP), and gamma-glutamyl-transaminase (GGT) levels increased, while albumin (ALB) levels decreased. Hepatocyte degeneration, lobular disorder, sinusoid dilation, focal necrotic areas, hyperemia, and glycogen loss were observed. Hepatic fibrosis was observed around portal areas and central veins. Bridging fibrous septa were formed between portal veins. By immunohistochemistry, both matrix metalloproteinase-9 (MMP-9) and desmin reactivity were increased. All aspects of liver damage were at least partially prevented in rats treated with vitamin D. Vitamin D appears to act as an antioxidant and anti-fibrotic to protect the rat liver against damage. 相似文献