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2-Hydroxylation of Acinetobacter baumannii Lipid A Contributes to Virulence.


ABSTRACT: Acinetobacter baumannii causes a wide range of nosocomial infections. This pathogen is considered a threat to human health due to the increasingly frequent isolation of multidrug-resistant strains. There is a major gap in knowledge on the infection biology of A. baumannii, and only a few virulence factors have been characterized, including lipopolysaccharide. The lipid A expressed by A. baumannii is hepta-acylated and contains 2-hydroxylaurate. The late acyltransferases controlling the acylation of lipid A have been already characterized. Here, we report the characterization of A. baumannii LpxO, which encodes the enzyme responsible for the 2-hydroxylation of lipid A. By genetic methods and mass spectrometry, we demonstrate that LpxO catalyzes the 2-hydroxylation of the laurate transferred by A. baumannii LpxL. LpxO-dependent lipid A 2-hydroxylation protects A. baumannii from polymyxin B, colistin, and human ?-defensin 3. LpxO contributes to the survival of A. baumannii in human whole blood and is required for pathogen survival in the waxmoth Galleria mellonella LpxO also protects Acinetobacter from G. mellonella antimicrobial peptides and limits their expression. Further demonstrating the importance of LpxO-dependent modification in immune evasion, 2-hydroxylation of lipid A limits the activation of the mitogen-activated protein kinase Jun N-terminal protein kinase to attenuate inflammatory responses. In addition, LpxO-controlled lipid A modification mediates the production of the anti-inflammatory cytokine interleukin-10 (IL-10) via the activation of the transcriptional factor CREB. IL-10 in turn limits the production of inflammatory cytokines following A. baumannii infection. Altogether, our studies suggest that LpxO is a candidate for the development of anti-A. baumannii drugs.

SUBMITTER: Bartholomew TL 

PROVIDER: S-EPMC6434125 | biostudies-literature | 2019 Apr

REPOSITORIES: biostudies-literature

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2-Hydroxylation of <i>Acinetobacter baumannii</i> Lipid A Contributes to Virulence.

Bartholomew Toby L TL   Kidd Timothy J TJ   Sá Pessoa Joana J   Conde Álvarez Raquel R   Bengoechea José A JA  

Infection and immunity 20190325 4


<i>Acinetobacter baumannii</i> causes a wide range of nosocomial infections. This pathogen is considered a threat to human health due to the increasingly frequent isolation of multidrug-resistant strains. There is a major gap in knowledge on the infection biology of <i>A. baumannii</i>, and only a few virulence factors have been characterized, including lipopolysaccharide. The lipid A expressed by <i>A. baumannii</i> is hepta-acylated and contains 2-hydroxylaurate. The late acyltransferases cont  ...[more]

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