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G Drews

Publications and source records attributed to G Drews.

At least 127 records · Page 7Linked to original sources
PubMed1978

Adsorption of cyanophage AS-1 to unicellular cyanobacteria and isolation of receptor material from Anacystis nidulans.

Cells of unicellular cyanobacteria of typological group Ia, containing approximately 50 mol% guanine + cytosine (G+C) in their DNA (R. Y. Stanier, R. Kunisawa, M. Mandel, and G. Cohen-Bazire, Bacteriol. Rev. 35:171-205, 1971), were susceptible to infection by the cyanophage AS-1. Cyanobacteria of the same typological group, containing approximately 65 mol% G+C in their DNA, did not adsorb the cyanophage AS-1 or adsorbed it at a low rate. AS-1 was not propagated by any of the investigated strains with a high G+C content in their DNA. However, cells of strains 6907 and 6911 were lysed by cyanophage AS-1. A comparison of the host range of this phage with the lipopolysaccharide composition of host and non-host cell walls suggests that lipopolysaccharides are involved in the adsorption process. About 8 microgram of lipopolysaccharide per ml from host strains inactivated 50% of the particles of a solution containing 100 PFU/ml after 60 min of incubation at 30 degrees C. Material with receptor activity was extracted from the host strain Anacystis nidulans KM. The extract was purified of glycolipids and pigments, and a fraction showing receptor activity was isolated. This fraction contained three polypeptides of molecular weights between 54,000 and 64,000. Heat and protease treatment of whole cells and of isolated receptor material decreased the receptor activity. The fluorescence intensity of A. nidulans cells labeled with 1-anilino-8-naphthalene sulfonate was increased when AS-1 was adsorbed to these cells. The participation of lipopolysaccharides and proteins in the formation of the receptor complex is discussed.

Adsorption↗
PubMed1977

Differentiation of the intracytoplasmic membrane of Rhodopseudomonas palustris induced by variations of oxygen partial pressure or light intensity.

The photosynthetic apparatus of Rhodopseudomonas palustris contains, in addition to reaction center bacteriochlorophyll (Bchl) two spectral forms of light harvesting (LH) Bchl, i.e. LH Bchl I, characterized by an infrared absorption maximum at 880 nm (890 nm at 77 degrees K) and LH Bchl II absorbing at 805 and 855 nm (805 and 870 nm at 77 degrees K). LH Bchl I seems to be associated with a single protein species of an apparent mol. wt. of 13 000 whereas LH Bchl II is apparently associated with two proteins of mol. wts. of 9000 and 11 000. Cells in anaerobic cultures adapt to changes of light intensity 1. by variation of the size of the photosynthetic unit, i.e. the molar ratio of LH Bchl II to reaction center Bchl, 2. by variation of the number of photosynthetic units per unit of membrane area, 3. by regulation of the size of the intracytoplasmic membrane system. During adaptation of changes of oxygen partial pressure cells are able to synthesize reaction center Bchl, LH Bchl and intracytoplasmic membranes at different rates. The synthesis of reaction center Bchl and LH Bchl I are, however, coordinated with each other, while the synthesis of LH Bchl II and reaction center Bchl proceed independently.

Adaptation, Biological↗
PubMed1977

Lipophilic O-antigens in Rhodospirillum tenue.

Lipopolysaccharides of eight wild-type strains of the phototrophic bacterium Rhodospirillum tenue have been analyzed. All of the lipopolysaccharides are highly lipophilic. The compositions of preparations obtained by the phenol-water or by the phenol-chloroform-petroleum ether procedure are very similar. The polysaccharide moiety, obtained by mild acid hydrolysis of lipopolysaccharide, consists mainly of aldoheptoses: L-glycero-D-mannoheptose is present in all strains, whereas D-glycero-D-mannoheptose is an additional constituent in some strains. Galactosaminuronic acid and two unknown ninhydrin-positive components were detected in the lipopolysaccharides of six strains. Spermidine and putrescine are present in large amounts in a salt-like linkage in the lipopolysaccharides from three strains. 2-Keto-3-deoxyoctonate forms the linkage between the polysaccharide moiety and lipid A. The lipid A fraction contains all the glucosamine and all the D-arabinose present in the lipopolysaccharide. D-Arabinose is an invariable constituent of the lipid A from the Rhodopseudomonas tenue lipopolysaccharides investigated. The principal fatty acids are beta-hydroxycapric, myristic, and palmitic acids. The isolated R. tenue lipopolysaccharides (O-antigens) react with rabbit antisera prepared against homologous cells. The titers in passive hemagglutination are low, similar to those found with enterobacterial R-lipopolysaccharides. R. tenue O-antigens containing only L-glycero-D-mannoheptose and those containing both the L- and D-epimers of glycero-D-mannoheptose could not be differentiated by serological means.

Amines↗
PubMed1976

Isolation and partial characterization of the cytochrome oxidase from Rhodopseudomonas palustris.

The cytochrome oxidase (EC 1.9.3.1) of Rhodopseudomonas palustris was extracted with Triton X-100 plus KCl, from the membrane fraction of cells grown aerobically in the dark. The solubilized enzyme was purified by (NH4)2SO4 precipitation and chromatography on DEAE-cellulose. The purification resulted in a 108-fold enrichment of cytochrome oxidase on the basis of specific activity when compared to the membrane fraction. The purified enzyme was phosphate-sensitive (less than mM), oxidized reduced bovine, horse and yeast cytochrome c, and was inhibited 50% by 0.5 muM KCN or 7 muM NaN3. The native purified preparation migrated as one band in polyacrylamide gel electrophoresis. In the presence of dodecylsulfate four major polypeptides with apparent molecular weights of 30500, 25500, 12200 and 9500 were observed. The enzyme reacted with oxygen via cytochrome o. The purified preparation contained cytochrome c but was free of flavoproteins and NADH-linked and succinate-linked enzyme activities of the respiratory chain.

Aerobiosis↗
PubMed1975

Control of composition and activity of the photosynthetic apparatus of Rhodopseudomonas capsulata grown in ammonium-limited continuous culture.

Rhodopseudomonas capsulata was grown either phototropically in the light or chemotrophically in the dark at oxygen tensions of 5 mm and 3 mm Hg in ammonium-limited continuous culture. During growth limitation bacteriochlorophyll content of cells and membranes varied dependent on growth rate drastically in chemotrophic cultures. Concomittantly, the ratio of membrane protein to total protein varied in the range of 30-41%. This dependence of membrane differentiation on growth rate was less evident in phototrophically grown cells. The incorporation of the bulk of bacteriochlorophyll was shown to be quantitatively correlated to the incorporation of 1-3 low molecular weight proteins with molecular weights in the range of 14 to less than 10 k daltons. Supported by similar findings of other authors it is proposed, that these proteins are to be attributed to the species of antenna bacteriochlorophyll and represent components of the photosynthetic apparatus. With decreasing growth rates the size of the photosynthetic unit with respect to the population of bacteriochlorophyll- and protein molecules was reduced subsequent to a reduction in the rate of incorporation of antenna-bacteriochlorophyll and the low molecular weight proteins, the reaction-center bacteriochlorophyll content of the membranes remaining constant. A parallel decrease in potential phosphorylating capacity was observed. It is concluded, that under these conditions, primary photochemical reactions in the reaction center were not the rate-limiting step in photophosphorylation. The interaction of growth limitation by an anabolic precursor (NH+4) and control of membrane differentiation by light intensity or oxygen tension is discussed.

Adenosine Triphosphate↗
PubMed1975

Photochemical reaction centers from Rhodopseudomonas capsulata.

A photochemically active bacteriochlorophyll-protein complex (reaction center) has been isolated from the carotenoidless mutant A1a+ of Rhodopseudomonas capsulata by treatment of membranes with lauryl dimethyl amine oxide. Three proteins with molecular weights of 20,500, 24,000 and 28,000 (molar ratio 1:1:1) were detected in the reaction center preparations. After mild treatment of intracytoplasmic membranes with Na-dodecyl sulfate (0.5%, 30 degrees C, 1 min) succeeded by polyacrylamide gel electrophoresis two pigmented bands were obtained. Material of one fraction could be bleached reversibly by actinic light and contained two proteins with molecular weights of 20,500 and 24000. The second band is photochemically inactive.

Bacterial Proteins↗
PubMed1975

Formation of reaction centers and light-harvesting bacteriochlorophyll-protein complexes in Rhodopseudomonas capsulata.

Formation of the photosynthetic apparatus was induced in aerobically grown dark cultures of Rhodopseudomonas capsulata by lowering of the oxygen tension. Besides the wild type strain the carotenoid-less mutant strain A1a+ was investigated. Both strains exhibited initially a decrease of the molar ratio of total bacteriochlorophyll (Bchl) to reaction center (RC) Bchl, followed by an increase. Synthesis of RC-Bchl preceded the synthesis of light-harvesting (LH) Bchl. Activities of photophosphorylation in membrane preparations, isolated from cultures after different periods of incubation at low aeration, decreased on the basis of total Bchl from about 9 to 2 mumole ATP/mumole total Bchl-min, whereas the rate on the basis of RC-Bchl remained constant (about 500 mumole ATP/mumole RC-Bchl-min). Under the same conditions the membrane proteins were labelled with U-14C-protein hydrolysate. Corresponding to RC-Bchl the synthesis of RC-proteins dominated during the first 30 min of incubation at PO2 below 3 mm Hg. After 45-60 min of membrane formation at low aeration the synthesis of LH-complex proteins exceeded the synthesis of RC proteins. The correlations between protein and Bchl synthesis in the sequential formation of RC- and LH-complexes are discussed.

Autoradiography↗
PubMed1975

Electron transport in an in vitro-reconstituted bacterial photophosphorylating system.

Photooxidation of endogenous cytochrome(s) c, photoreduction of endogenous chrome(s) b and photobleaching of bacteriochlorophyll have been demonstrated in an in vitro reconstituted system, previously demonstrated to support photophosphorylation. The kinetic responses of these redox reactions to substrate and antimycin A in these particle are characteristic of electron transport processes and stronglysupport the contention that all, or a part of, the oxidative phosphorylation electron transport pathway can be coupled to reaction center, photopigment complex in a manner which supports photophosphorylation. In addition, a succinate-supported light dependent reduction of NAD+ was found.

Antimycin A↗
PubMed1975

The respiratory electron transport system of heterotrophically-grown Rhodopseudomonas palustris.

The enzymatic activities and the cytochrome components of the respiratory chain were investigated with membrane fractions from chemoheterotrophically growth Rhodopseudomonas palustris. Whereas the level of electron transfer carriers was not distinctly affected by a change of the culture conditions, the potential activities of the enzymes were clearly increased when the cells were grown aerobically. Reduced-minus oxidized difference spectra of the membrane fractions prepared from dark aerobically grown cells revealed the presence of three beta-types cytochromes b561, b560 and b558, and at least two c-type cytochromes c556 and c2 as electron carriers in the electron transfer chain. Cytochrome of a-type could not be detected in these membranes. Reduced plus CO minus reduced difference spectra of the membrane fractions were indicative of cytochrome o, which may be equivalent to cytochrome b560, appearing in substrate-reduced minus oxidized difference spectra. Cytochrome o was found to be the functional terminal oxidase. CO difference spectra of the high speed supernatant fraction indicated the presence of cytochrome c'. Succinate and NADH reduced the same types of cytochromes. However, a considerable amount of cytochrome b561 with associated beta and gamma bands at 531 and 429 nm, respectively, was reducible by succinate, but not by NADH. A substantial fraction of the membrane-bound b-type cytochrome was non-substrate reducible and was found in dithionite-reduced minus substrate-reduced spectra. Cytochrome c2 may be localized in a branch of the electron transport system, with the branch-point at the level of ubiquinone. The separate pathways rejoined at a common terminal oxidase. Two terminal oxidases with different KCN sensitivity were present in the respiratory chain, one of which was sensitive to low concentrations of KCN and was connected with the cytochrome chain. The other terminal oxidase which was inhibited only by high concentrations of cyanide was located in a branched pathway, through which the electrons could flow from ubiquinone to oxygen bypassing the cytochrome chain.

Aerobiosis↗
PubMed1975

Lipophilic O-antigens containing D-glycero-D-mannoheptose as the sole neutral sugar in Rhodopseudomonas gelatinosa.

Lipopolysaccharides (LPS, O-antigens) of 12 strains of the photosynthetic bacterium Rhodopseudomonas gelatinosa were obtained by the phenol/chloroform/petroleum ether method, recommended for extracting lipophilic glycolipids of enterobacterial R-mutants. All R. gelatinosa LPS have essentially the same chemical composition. Similar to LPS of Salmonella R-mutants of chemotypes Rd1 and Rd2, the sole neutral sugar constituent is an aldoheptose. The heptose of R. gelatinosa LPS has the D-glycero-D-manno- configuration, in contrast to the L-glycero-D-mannoheptose of enterobacterial LPS. 2-Keto-3-deoxyoctonate forms the acid-labile linkage between the lipid moiety (lipid A) and the oligosaccharide moiety of R. gelatinosa LPS. Like enterobacterial lipid A, lipid A of this species contains phosphate and D-glucosamine as the sole amino sugar. The fatty acid spectrum conprises beta-hydroxycapric, lauric, and myristic acids. Beta-Hydroxymyristic acid, the typical fatty acid of enterobacterial LPS, is lacking. The R. gelatinosa LPS show O-antigenic acitivity; passive hemagglutinations with untreated or heat-treated (not well alkali-treated) LPS and antisera prepared against heat-killed cells yield high titers. According to the serological cross-reactions observed, the LPS of the 12 strains could be arranged into two different serotypes: serotype I comprising strains 29/1, 29/2, 25/2, and serotype II comprising strains 44/K/6, 3/1, IS/10, 39/2, Dr2, 2150, P8P9, K32, P18f3.1. No serological cross-reactions were observed between LPS of these two different serotypes in passive hemagglutinations.

Caprylates↗
PubMed1975

Low-molecular-weight polysaccharide antigens isolated from Rhodopseudomonas gelatinosa.

Strain-specific low-molecular-weight polysaccharides of different chemical compositions were obtained from cells of nine different wild-type strains of the phototrophic bacterium Rhodopseudomonas gelatinosa. The polysaccharides are free of typical capsule components like hexuronic or aminohexuronic acids but contain (except that of strain 39/2) substantial amounts of phosphorus. A number of unusual o-methyl sugars (2-o-methyl-D-galactose, 2,3-di-o-methyl-D-galactose, 2-o-methyl-L-fucose) as well as 3,6-dideoxy-D-xylo-hexose (abequose) were identified in the R. gelatinosa polysaccharides. o-Methyl and dideoxy sugars however, are typical constituents of O-specific chains of the lipopolysaccharides of gram-negative bacteria (Rhodospirillaceae and Enterobacteriaceae, respectively). Considering both the R-type character of the R. gelatinosa lipopolysaccharides and the occurrence of these strain-specific ETEROPOLYSACCHARIDES, THE ASSUMPTION SEEMS TO BE JUSTIFIED THAT THE LOW-MOLECULAR-WEIGHT POLYSACCHARIDES ARE RELATED TO O-specific chains of lipopolysaccharides (haptens) rather than to capsular or slime antigens. In serological terms the polysaccharides of R. gelatinosa have to be classified as K-antigens. They are able to cover the O-specificity of the respective different strains and confer on them additional specificity which is demonstrable by bacterial agglutination.

Cross Reactions↗
PubMed1974

On reconstitution of bacterial photophosphorylation in vitro.

Membranes active in oxidative phosphorylation but inactive in photophosphorylation were isolated from a carotenoid-less and bacteriochlorophyll-less mutant strain of Rhodopseudomonas capsulata. These membranes were uncoupled and recombined with coupling factor from the same strain and with reaction centers from a photosynthetically active revertant strain. The reconstituted system was able to form ATP from ADP and inorganic phosphate under anaerobic conditions in the light. Rates of 2 nmoles of ATP formed per min per mug of bacteriochlorophyll were obtained. A high incorporation of (32)P from inorganic phosphate into ADP in the light as well as in the dark was observed, the activity of which was associated with coupling factor. This incorporation occurs both aerobically and anaerobically and appears to be independent of photophosphorylation.

Adenosine Diphosphate↗