Affiliation:
1. Department of Molecular Biology, Princeton University, Princeton, New Jersey, USA
2. Lewis-Sigler Institute for Integrative Genomics, Princeton University, Princeton, New Jersey, USA
Abstract
ABSTRACT
In Gram-negative bacteria, lipopolysaccharide (LPS) contributes to the robust permeability barrier of the outer membrane, preventing entry of toxic molecules such as antibiotics. Mutations in
lptD
, the beta-barrel component of the LPS transport and assembly machinery, compromise LPS assembly and result in increased antibiotic sensitivity. Here, we report rare vancomycin-resistant suppressors that improve barrier function of a subset of
lptD
mutations. We find that all seven suppressors analyzed mapped to the essential gene
cdsA
, which is responsible for the conversion of phosphatidic acid to CDP-diacylglycerol in phospholipid biosynthesis. These
cdsA
mutations cause a partial loss of function and, as expected, accumulate phosphatidic acid. We show that this suppression is not confined to mutations that cause defects in outer membrane biogenesis but rather that these
cdsA
mutations confer a general increase in vancomycin resistance, even in a wild-type cell. We use genetics and quadrupole time of flight (Q-TOF) liquid chromatography-mass spectrometry (LC-MS) to show that accumulation of phosphatidic acid by means other than
cdsA
mutations also increases resistance to vancomycin. We suggest that increased levels of phosphatidic acid change the physical properties of the outer membrane to impede entry of vancomycin into the periplasm, hindering access to its target, an intermediate required for the synthesis of the peptidoglycan cell wall.
Publisher
American Society for Microbiology
Subject
Molecular Biology,Microbiology
Cited by
34 articles.
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