Chemical analyses on cell envelope polymers of the halophilic,phototrophic Rhodospirillum salexigens |
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Authors: | D Evers J Weckesser U J Jürgens |
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Institution: | (1) Institut für Biologie II, Mikrobiologie, der Albert-Ludwigs-Universität, Schänzlestr. 1, D-7800 Freiburg i. Br., Federal Republic of Germany |
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Abstract: | Whole cells of Rhodospirillum salexigens, an obligatory halophilic bacterium, have a very low peptidoglycan content (0.17 mol muramic acid/mg cell dry weight) which is not sufficient to form a sacculus structure. The isolated peptidoglycan contains glucosamine: muramic acid: diaminopimelic acid: alanine: glutamic acid in molar ratios of 1:1:1:2:3. The degree of cross linking is 30%. A polysaccharide consisting of glucosamine, an unknown compound X and a 2-amino-2-deoxy-pentose (relative molar ratios; 1:2:1) was extracted into the water phase of phenol water extracts of whole cells. The polysaccharide co-sedimented with peptidoglycan when cell homogenates were centrifuged in the presence of 4% NaCl (100,000xg, 4 h) or on a sucrose gradient (20–60% sucrose, 28,000xg, 16 h) in the presence or absence of NaCl and/or EDTA.Lack of -hydroxy fatty acids and of 2-keto-3-deoxyoctonate in all phenol-water extract fractions as well as in the whole cell hydrolysate indicates the absence of common outer membrane lipopolysaccharide in R. salexigens. Removal of the cell surface layer exposed six proteins to labeling with radioactive iodine catalyzed by lactoperoxidase. These proteins are suggested to be constituents of the outer membrane of R. salexigens.Abbreviations Ala
alamine
- A2pm
diaminopimelic acid
- DDPT
dimethyl-3,3 -dithiobispropionimidate dihydrochloride
- GlcN
glucosamine
- Glu
glutamic acid
- Gly
glycine
- His
histidine
- MurN
muramic acid
- SDS
sodium dodecyl sulfate |
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Keywords: | Cell envelope Halophilic Rhodospirillum salexigens |
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