Lipopolysaccharide synthesis in Yersinia pseudotuberculosis O:1b serovar: influence of 82-megadalton plasmid and bacterial growth temperature

摘要

Lipopolysaccharides from the "cold" (8 deg C) and "warm" (37 deg C) variants of isogenic Yersinia pseudotuberculosis O:1b serovar strains (plasmid free (82~-) and infected with the homologous pVM82 (82~+) or p57 (57~+) plasmids) were isolated and characterized by SDS-PAGE, ~(13)C-NMR-spectroscopy, and various chemical and immunochemical methods. In the cold, the S-form LPSs of an identical structure with a high acylation degrees and immunochemical activities distinguishing in polymerization degreeswere synthesized in the (82~-) and (82~+) strains. (LPSs of the (82~-) strain had longer carbohydrate chains than LPSs of the (82~+) strain). A thermoadaptive reaction of the plasmidless strain was typical for Y. pseudotuberculosis: its "warm" variant was characterized by low LPS content and its LPS was of the R-form, had a low acylation degree, and was immunochemically inactive. In the (82~+) strain, the general content of LPS was found to poorly depend on cultivation temperatures; LPS of these bacteria included a polysaccharide fragment and displayed moderate immunochemical activity. In the cells of the (57~+) strain, LPS was deficient at both cultivation temperatures, its LPSs were of a low acylation degree and did not contain O-specific side chains (the "cold" variant) or contained O-polysaccharide of a low polymerization degree (in bacteria grown at 37 deg C). Based on the research conducted, the following conclusions are made. LPS synthesis in the plasmidless Y. pseudotuberculosis strain is coded by chromosomal genes. Expression of the genes controlling this process is regulated by growth temperature. The genes responsible for a thermoregulation of LPS synthesis are located on a chromosome. Plasmid pVM82 has two groups of the genes. Its 57-mDmoiety inhibits LPS synthesis and cancels the dependence of LPS synthesis on bacterial growth temperature. A 25-mD fragment seems to act as a derepressor of the function of the 57-mD moiety, restoring the ability of the plasmid-containing strain to synthesize more or less long LPS at both growth temperatures.