Affiliation:
1. Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, Michigan 48109
Abstract
ABSTRACT
Curli are extracellular surface fibers that are produced by many members of the
Enterobacteriaceae
and contribute to biofilm formation. The environmental cues that promote biofilm formation are poorly understood. We found that deletion of the
N
-acetylglucosamine-6-phosphate (GlcNAc-6P) deacetylase gene,
nagA
, resulted in decreased transcription from the curli-specific promoters
csgBA
and
csgDEFG
and a corresponding decrease in curli production in
Escherichia coli. nagA
is in an operon that contains
nagB
,
nagC
,
nagD
, and
nagE
, whose products are required for utilization of GlcNAc as a carbon source. NagC is a repressor of the
nagBACD
and
nagE
genes in the absence of intracellular GlcNAc-6P. We found that
nagC
mutants were also defective in curli production. Growth of a wild-type strain on media containing additional GlcNAc reduced curli gene transcription to a level similar to the level observed when
nagA
was deleted. The defect in curli production in
nagA
or
nagC
mutants was alleviated by deletion of the GlcNAc transporter gene,
nagE
. Curli-producing Δ
nagA
suppressor mutants whose cells were unable to take up GlcNAc were isolated. These results suggest that elevated levels of intracellular GlcNAc-6P signal cells to down-regulate curli gene expression.
Publisher
American Society for Microbiology
Subject
Molecular Biology,Microbiology
Cited by
50 articles.
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