PMID:16704973

Citation	Reynolds, CM, Ribeiro, AA, McGrath, SC, Cotter, RJ, Raetz, CR and Trent, MS (2006) An outer membrane enzyme encoded by Salmonella typhimurium lpxR that removes the 3'-acyloxyacyl moiety of lipid A. J. Biol. Chem. 281:21974-87
Abstract	The Salmonella and related bacteria modify the structure of the lipid A portion of their lipopolysaccharide in response to environmental stimuli. Some lipid A modifications are required for virulence and resistance to cationic antimicrobial peptides. We now demonstrate that membranes of Salmonella typhimurium contain a novel hydrolase that removes the 3'-acyloxyacyl residue of lipid A in the presence of 5 mM Ca2+. We have identified the gene encoding the S. typhimurium lipid A 3'-O-deacylase, designated lpxR, by screening an ordered S. typhimurium genomic DNA library, harbored in Escherichia coli K-12, for expression of Ca2+-dependent 3'-O-deacylase activity in membranes. LpxR is synthesized with an N-terminal type I signal peptide and is localized to the outer membrane. Mass spectrometry was used to confirm the position of lipid A deacylation in vitro and the release of the intact 3'-acyloxyacyl group. Heterologous expression of lpxR in the E. coli K-12 W3110, which lacks lpxR, resulted in production of significant amounts of 3'-O-deacylated lipid A in growing cultures. Orthologues of LpxR are present in the genomes of E. coli O157:H7, Yersinia enterocolitica, Helicobacter pylori, and Vibrio cholerae. The function of LpxR is unknown, but it could play a role in pathogenesis because it might modulate the cytokine response of an infected animal.
Links	PubMed PMC2702521 Online version:10.1074/jbc.M603527200
Keywords	Bacterial Proteins/genetics; Bacterial Proteins/metabolism; Carboxylic Ester Hydrolases/genetics; Carboxylic Ester Hydrolases/metabolism; Gene Library; Lipid A/metabolism; Mass Spectrometry; Membrane Proteins/genetics; Membrane Proteins/metabolism; Molecular Sequence Data; Protein Sorting Signals; Salmonella typhimurium/enzymology
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Annotations

Gene product	Qualifier	GO Term	Evidence Code	with/from	Aspect	Extension	Notes	Status
SALTY:Q8ZPT3		GO:0031308 : intrinsic to nuclear outer membrane	ECO:0000314:		C		Detection of a novel 3′-O-deacylase in membranes of wild type S. typhimurium strain LT2 (figure 3).Presence of 3′-O-deacylase in membranes of E. coli NovaBlue(DE3)-expressing LpxR (Figure 4). An outer membrane enzyme encoded by Salmonella typhimurium lpxR that removes the 3'-acyloxyacyl moiety of lipid A	complete

References

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