期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：2013
卷号：110
期号：4
页码：1470-1475
DOI：10.1073/pnas.1215416110
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：Gram-negative bacteria have an outer membrane containing LPS. LPS is constituted of an oligosaccharide portion and a lipid-A moiety that embeds this molecule within the outer membrane. LPS is a pathogen-associated molecular pattern, and several pathogens modify their lipid-A as a stealth strategy to avoid recognition by the innate immune system and gain resistance to host factors that disrupt the bacterial cell envelope. An essential feature of Salmonella enterica Typhimurium pathogenesis is its ability to replicate within vacuoles in professional macrophages. S. Typhimurium modifies its lipid-A by hydroxylation by the Fe2+/-ketoglutarate-dependent dioxygenase enzyme (LpxO). Here, we show that a periplasmic protein of the bacterial oligonucleotide/oligosaccharide-binding fold family, herein named virulence and stress-related periplasmic protein (VisP), on binding to the sugar moiety of peptidoglycan interacts with LpxO. This interaction inhibits LpxO function, leading to decreased LpxO-dependent lipid-A modifications and increasing resistance to stressors within the vacuole environment during intramacrophage replication promoting systemic disease. Consequently, {Delta}visP is avirulent in systemic murine infections, where VisP acts through LpxO. Several Gram-negative pathogens harbor both VisP and LpxO, suggesting that this VisP-LpxO mechanism of lipid-A modifications has broader implications in bacterial pathogenesis. Bacterial species devoid of LpxO (e.g., Escherichia coli) have no lipid-A phenotypes associated with the lack of VisP; however, VisP also controls LpxO-independent phenotypes. VisP and LpxO act independently in the S. Typhimurium murine colitis model, with both mutants being attenuated for diverging reasons; {Delta}visP is less resistant to cationic antimicrobial peptides, whereas {Delta}lpxO is deficient for epithelial cell invasion. VisP converges bacterial cell wall homeostasis, stress responses, and pathogenicity.
