Identification of cptA, a PmrA-regulated locus required for phosphoethanolamine modification of the Salmonella enterica serovar typhimurium lipopolysaccharide core.
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.
Tamayo
R
R
Department of Microbiology and Immunology, University of Texas Health Science Center at San Antonio, San Antonio, Texas 78229-3900, USA.
Choudhury
B
B
Septer
A
A
Merighi
M
M
Carlson
R
R
Gunn
J S
JS
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
D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; D004983:Ethanolamines; D008070:Lipopolysaccharides; C005448:phosphorylethanolamine; D004982:Ethanolaminephosphotransferase; C106234:CptA protein, bacteria; D010450:Endopeptidases; D011112:Polymyxin B