2Department of Immunology, Biological Faculty, Lomonosov Moscow State University, 119991 Moscow, Russia
3Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, 119991 Moscow, Russia
4Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences, Leninsky pr. 47, 119991 Moscow, Russia; fax: (499) 135-5328; E-mail: firstname.lastname@example.org
5Institute for Physicochemical and Biological Problems in Soil Science, Russian Academy of Sciences, 142290 Pushchino, Moscow Region, Russia; fax: (4967) 33-0532; E-mail: email@example.com
6State Research Center for Applied Microbiology and Biotechnology, 142279 Obolensk, Moscow Region, Russia; fax: (4967) 36-0010; E-mail: firstname.lastname@example.org
* To whom correspondence should be addressed.
# These authors contributed equally to this work.
Received June 30, 2014
Correlation between the chemical structure of lipid A from various Gram-negative bacteria and biological activity of their lipopolysaccharide (LPS) as an agonist of the innate immune receptor Toll-like receptor 4 was investigated. Purified LPS species were quantitatively evaluated by their ability to activate the production of tumor necrosis factor (TNF) by murine bone marrow-derived macrophages in vitro. Wild-type LPS from plague-causing bacteria Yersinia pestis was compared to LPS from mutant strains with defects in acyltransferase genes (lpxM, lpxP) responsible for the attachment of secondary fatty acid residues (12:0 and 16:1) to lipid A. Lipid A of Y. pestis double ΔlpxM/ΔlpxP mutant was found to have the chemical structure that was predicted based on the known functions of the respective acyltransferases. The structures of lipid A from two members of the ancient psychrotrophic bacteria of the genus Psychrobacter were established for the first time, and biological activity of LPS from these bacteria containing lipid A fatty acids with shorter acyl chains (C10-C12) than those in lipid A from LPS of Y. pestis or E. coli (C12-C16) was determined. The data revealed a correlation between the ability of LPS to activate TNF production by bone marrow-derived macrophages with the number and the length of acyl chains within lipid A.
KEY WORDS: lipopolysaccharide, lipid A, Toll-like receptor 4, tumor necrosis factor, Yersinia pestis, Psychrobacter spp.