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I Fromme

Publications and source records attributed to I Fromme.

12 recordsLinked to original sources
PubMed1979

A membrane glycoprotein of aggregating Dictyostelium cells with the properties of contact sites.

Aggregating cells of Dictyostelium discoideum form EDTA-stable contacts which are blocked by a Fab (antigen-binding fragment) preparation from antisera raised against membranes. The target site of the blocking Fab fragments has been identified as a specific glycoprotein. In this paper its purification, carbohydrate and amino acid composition are described. Purification was 800-fold, starting with cells lysed by digitonin. The plasma membranes, preserved as ghosts by this treatment, were purified in a two-phase system and extracted with butan-1-ol. The water phase contained predominantly concanavalin-A-binding glycoproteins and was particularly rich in contact sites A. These were further purified on DE-cellulose and sucrose gradients. Sodium dodecylsulphate/polyacrylamide gel electrophoresis of the purified material revealed one major glycoprotein band in the molecular weight region of 80 000 to 90 000, depending on the acrylamide concentration. The sugars found in contact sites A were mannose, N-acetylglucosamine, fucose, and possibly glucose. The protein moeity contained 8% proline and was particularly rich in hydroxy amino acids.

Amino Acids↗
PubMed1977

Ribitol-containing lipopolysaccharides from Proteus mirabilis and their serological relationship.

Ribitol phosphate was recently identified as a constituent of lipopolysaccharides obtained from 'proteus mirabilis strain D52 giving 1:4-anhydroribitol during acid hydrolysis (Gmeiner, 1975). Two other Proteus mirabilis strains belonging to serogroups O16 and O33 were shown previously to contain an unknown compoound X as lipopolysaccharide constituent (Kotelko et al., 1975). In this report the identification of compound X as 1:4-anhydroribotol by gas-liquid chromatography, mass spectrometry and mass fragmentography is described. Serological investigations using passive hemagglutination, hemagglutination inhbition and semi-quantitative precipitin reactions indicate strongly that ribitol plays a role in the serological specificity of the respective lipopolysaccharides.

Hemagglutination Inhibition Tests↗
PubMed1976

Isolation and characterization of the lipopolysaccharide of Chromatium vinosum.

Lipolysaccharide was isolated from Chromatium vinosum by phenol/water extraction. The lipopolysaccharide is found exclusively in the phenol phase and can be cleaved into a sugar moiety and a lipid A fraction by hydrolysis in 10% acetic acid at 100 degrees C for 3-4 h. The sugar moiety contains the neutral sugars 3-O-methyl-D-ribose, D-ribose, L-arabinose, mannosamine and glucose, and smaller quantities of D-rhamnose, D-glycero-D-manno-heptose (tentatively identified), quinovosamine and 2-keto-3-deoxyoctonate. L-glycero-D-manno-heptose was not detected. The 2-keto-3-deoxyoctonate linkage in C. vinosum lipopolysaccharide is more resistant to acid hydrolysis than that of Escherichia coli. The lipid A fraction contains glucosamine, mannose and the fatty acids of the lipopolysaccharide. The major fatty acid is beta-hydroxymyristic acid, with smaller amounts of lauric and palmitic acids as well as 14-carbon mono-unsaturated fatty acid, also being present. The phosphorus content of the C. vinosum lipopolysaccharide was found to be approximately 0.1%. Erythrocytes sensitized with alkali-treated C. vinosum lipopolysaccharide were agglutinated by antisera prepared against heat-killed cells. Untreated or heat-treated lipopolysaccharide did not sensitize erythrocytes. The lethal toxicity to mice of the C. vinosum lipopolysaccharide is about one-tenth as that from Salmonella abortus equi.

Animals↗
PubMed1976

[Investigations on the fatty acid composition of lipids from Salmonella minnesota S and R forms (author's transl)].

Non-covalently bound lipids were extracted from 2 Salmonella minnesota S forms and 5 R mutants (chemotype Ra-Re) isolated from these strains. The lipids were subsequently analysed with regard to fatty acid composition. The extracts were free of lipid A, as determined by absence of beta-hydroxymyristic acid. The fatty acid distribution in the lipids of the two S forms, cultivated at 37 degrees C to the beginning of the stationary phase of growth, agreed very closely, and the values corresponded to those reported in the literature for S. typhimurium. In contrast, there was a progressive reduction in the content of C17- and C19-cyclopropane fatty acids, going from Ra-Rc mutants. The total cyclopropane fatty acids decreased from approximately 30% (Ra) to approximately 7% (Rc). The lipids from the Rd1 and the Re mutants had a fatty acid composition identical to that of the Rc mutant. The decrease in cyclopropane fatty acid content was compensated for in all strains by an increase in the corresponding unsaturated fatty acids (16:1; 18:1). Variations in the incubation temperature (30, 37, 41 degrees C) affected the ratio of the single fatty acids as determined for the Ra, Rc and Re mutants. The content of unsaturated fatty acids increased with the reduction in temperature, while the proportion of cyclopropane fatty acids decreased (stationary growth phase). These changes were much more pronounced with the Ra mutant than with the Rc and the Re mutants. The differences among the mutants with regard to fatty acid distribution were apparent at all temperature levels. In addition, the fatty acid composition of the lipids varied with the phase of growth, as already reported for E. coli and other gram-negative organisms. The content of cyclopropane fatty acids increased from the exponential to the stationary phases, with simultaneous reduction in the proportion of corresponding unsaturated fatty acids. Again, the lipid composition of the Ra mutant varied to a greater extent than did that of the Rc and the Re mutants. Similar changes appeared in the phosphatidyl ethanolamine fractions of the three mutants. There were also changes in the neutral lipids that agreed in part with those of the total lipids. The cause of the reduced cyclopropane fatty acid synthesis in S. minnesota R mutants possessing an incomplete LPS-core structure (Rb2-Re) is at present unknown. The physiological significance of these findings as well remains for the moment speculative, as the functional role of cyclopropane fatty acids in biological membranes has not yet been elucidated. Possible relations to membrane permeability and to transfer of antibiotics are discussed.

Cell Division↗
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↗
PubMed1975

[Chemical and serological characterization of Salmonella lipopolysaccharides from different phases of growth (author's transl)].

Chemical and serological investigations were carried out on lipopolysaccharides of 4 Salmonella S-forms and of 1 SR-mutant, extracted from bacteria at different ages of culture (early exponential to stationary growth phase). The results show that the fatty acid composition of Lipid A (lauric-, myristic-, palmitic-, and beta-hydroxy-myristic acids) does not undergo any significant change during the growth of the cultures. However, there are differences in the molar ratios of the fatty acids from strain to strain. In all phases of growth Lipid A is substituted by basaloligosaccharide, to the same extent, as can be seen from the constant ratios of beta-hydroxy-myristic acid: heptose. Serological experiments (haemagglutination inhibition tests, absorption of antibodies by LPS-coated erythrocytes) showed that in no case the basaloligosaccharide is completely substituted by O-specific chains and that basaloligosaccharide exhibits free R-antigen structures which are mainly of chemotypes Ra, Rb and Rc, for the SR-mutant only of types Ra and Rb. There is no demonstrable dependence upon the phases of growth. In the O-specific polysaccharide chains the sugars of the main chain and the side bound dideoxy sugars (abequose and tyvelose) show a constant 1:1 molar ratio in all phases. In the case of S. typhimurium, antigen factors 1, 4 and 12(2), the biosynthesis of which is controlled by modifying oaf genes and/or by a lysogenic phage, are of a somewhat weaker expression in the exponential phase than in the latter phases of growth. In the SR-mutant, lipopolysaccarides with (low) serological O1 and O12(2) activity are only extractable by the phenol/water method, but not by the PCP method. In three out of four S-forms, changes occur in the length of the O-specific polysaccharide chains, whereas the number of repeating units of the fourth strain remains almost unchanged. The lipopolysaccharides of the SR-mutant contain in all phases of growth about one repeating unit. In all strains the covering of the cell surface by lipopolysaccharide molecules changes during the course of growth, as can be seen by comparing the relative cell surface and the content of Lipid A fatty acids of the bacteria. Lipid A synthesis in the 4 S-forms is reduced in the exponential phase and/or in the phase of delayed growth acceleration. The extent of biosynthesis of the carbohydrate moiety of lipopolysaccharides is independent of that of Lipoid A. In the SR-mutant, Lipoid A and Polysaccharide are formed in increased amounts in the exponential growth phase.

Cell Wall↗