Affiliation:
1. Department of Microbiology and Immunology, Emory University, Atlanta, Georgia, USA
2. Research Service, Atlanta VA Medical Center, Decatur, Georgia, USA
3. Department of Physics, Emory University, Atlanta, Georgia, USA
Abstract
ABSTRACT
A key regulator of swarming in
Proteus mirabilis
is the Rcs phosphorelay, which represses
flhDC
, encoding the master flagellar regulator FlhD
4
C
2
. Mutants in
rcsB
, the response regulator in the Rcs phosphorelay, hyperswarm on solid agar and differentiate into swarmer cells in liquid, demonstrating that this system also influences the expression of genes central to differentiation. To gain a further understanding of RcsB-regulated genes involved in swarmer cell differentiation, transcriptome sequencing (RNA-Seq) was used to examine the RcsB regulon. Among the 133 genes identified,
minC
and
minD
, encoding cell division inhibitors, were identified as RcsB-activated genes. A third gene,
minE
, was shown to be part of an operon with
minCD
. To examine
minCDE
regulation, the
min
promoter was identified by 5′ rapid amplification of cDNA ends (5′-RACE), and both transcriptional
lacZ
fusions and quantitative real-time reverse transcriptase (qRT) PCR were used to confirm that the
minCDE
operon was RcsB activated. Purified RcsB was capable of directly binding the
minC
promoter region. To determine the role of RcsB-mediated activation of
minCDE
in swarmer cell differentiation, a polar
minC
mutation was constructed. This mutant formed minicells during growth in liquid, produced shortened swarmer cells during differentiation, and exhibited decreased swarming motility.
IMPORTANCE
This work describes the regulation and role of the MinCDE cell division system in
P. mirabilis
swarming and swarmer cell elongation. Prior to this study, the mechanisms that inhibit cell division and allow swarmer cell elongation were unknown. In addition, this work outlines for the first time the RcsB regulon in
P. mirabilis
. Taken together, the data presented in this study begin to address how
P. mirabilis
elongates upon contact with a solid surface.
Publisher
American Society for Microbiology
Subject
Molecular Biology,Microbiology
Cited by
25 articles.
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