Variation in Lipid A Structure in the Pathogenic Yersiniae
Important pathogens in the genus Yersinia include the plague bacillus Yersinia pestis and two enteropathogenic species, Yersinia pseudotuberculosis and Yersinia enterocolitica. A shift in growth temperature induced changes in the number and type of acyl groups on the lipid A of all three species. After growth at 37°C, Y. pestis lipopolysaccharide (LPS) contained the tetra-acylated lipid IVA and smaller amounts of lipid IVA modified with C10 or C12 acyl groups, Y. pseudotuberculosis contained the same forms as part of a more heterogeneous population in which lipid IVA modified with C16:0 predominated, and Y. enterocolitica produced a unique tetra-acylated lipid A. When grown at 21°C, however, the three yersiniae synthesized LPS containing predominantly hexa-acylated lipid A. This more complex lipid A stimulated human monocytes to secrete tumour necrosis factor-α, whereas the lipid A synthesized by the three species at 37°C did not. The Y. pestis phoP gene was required for aminoarabinose modification of lipid A, but not for the temperature-dependent acylation changes. The results suggest that the production of a less immunostimulatory form of LPS upon entry into the mammalian host is a conserved pathogenesis mechanism in the genus Yersinia, and that species-specific lipid A forms may be important for life cycle and pathogenicity differences.
Rebeil, R., Ernst, R.K., Gowen, B.B., Miller, S.I., and Hinnebusch, B.J. 2004. Variation in lipid A structure in the pathogenic yersiniae Mol. Microbiol. 52: 1363-73.
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