title: Identification of cptA, a PmrA-regulated locus required for phosphoethanolamine modification of the Salmonella enterica serovar typhimurium lipopolysaccharide core.
abstract: In response to the in vivo environment, the Salmonella enterica serovar Typhimurium lipopolysaccharide (LPS) is modified. These modifications are controlled in part by the two-component regulatory system PmrA-PmrB, with the addition of 4-aminoarabinose (Ara4N) to the lipid A and phosphoethanolamine (pEtN) to the lipid A and core. Here we demonstrate that the PmrA-regulated STM4118 (cptA) gene is necessary for the addition of pEtN to the LPS core. pmrC, a PmrA-regulated gene necessary for the addition of pEtN to lipid A, did not affect core pEtN addition. Although imparting a similar surface charge modification as Ara4N, which greatly affects polymyxin B resistance and murine virulence, neither pmrC nor cptA plays a dramatic role in antimicrobial peptide resistance in vitro or virulence in the mouse model. Therefore, factors other than surface charge/electrostatic interaction contribute to resistance to antimicrobial peptides such as polymyxin B.
authors.affiliation: Department of Microbiology and Immunology, University of Texas Health Science Center at San Antonio, San Antonio, Texas 78229-3900, USA.
authors.forename: R
authors.initials: R
authors.lastname: Tamayo
authors.forename: B
authors.initials: B
authors.lastname: Choudhury
authors.forename: A
authors.initials: A
authors.lastname: Septer
authors.forename: M
authors.initials: M
authors.lastname: Merighi
authors.forename: R
authors.initials: R
authors.lastname: Carlson
authors.forename: J S
authors.initials: JS
authors.lastname: Gunn
mesh_terms: D000818:Animals; D000900:Anti-Bacterial Agents / Q000378:metabolism; D001426:Bacterial Proteins / Q000235:genetics* / Q000378:metabolism*; D024881:Drug Resistance, Bacterial; D010450:Endopeptidases / Q000235:genetics* / Q000378:metabolism*; D004982:Ethanolaminephosphotransferase / Q000378:metabolism; D004983:Ethanolamines / Q000378:metabolism; D005260:Female; D008070:Lipopolysaccharides / Q000378:metabolism; D051379:Mice; D008807:Mice, Inbred BALB C; D009345:Neisseria meningitidis / Q000201:enzymology; D010284:Paratyphoid Fever / Q000382:microbiology*; D011112:Polymyxin B / Q000378:metabolism; D012486:Salmonella typhimurium / Q000235:genetics* / Q000378:metabolism* / Q000472:pathogenicity; D014774:Virulence
chemical_list: D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; D004983:Ethanolamines; D008070:Lipopolysaccharides; C005448:phosphorylethanolamine; D004982:Ethanolaminephosphotransferase; C106234:CptA protein, bacteria; D010450:Endopeptidases; D011112:Polymyxin B