Affiliation:
1. Department of Biological Sciences, Binghamton University, Binghamton, New York, USA
2. Physiology of Microorganisms, Ruhr-University Bochum, Bochum, Germany
Abstract
ABSTRACT
Dispersion is a process used by bacteria to successfully transit from a biofilm to a planktonic growth state and to spawn novel communities in new locales. Alterations in
bis
-(3′-5′)-cyclic dimeric GMP (c-di-GMP) levels have been shown to be associated with biofilm dispersal in a number of different bacteria. The signaling molecule nitric oxide (NO) is known to induce biofilm dispersion through stimulation of c-di-GMP-degrading phosphodiesterase (PDE) activity. However, no c-di-GMP modulating enzyme directly involved in NO-induced dispersion has yet been described in the opportunistic pathogen
Pseudomonas aeruginosa
. Here, we characterized MucR (PA1727) and NbdA (PA3311,
N
O-induced
b
iofilm
d
ispersion locus
A
), two membrane-bound proteins with identical domain organization consisting of MHYT-GGDEF-EAL, with respect to their role in NO-induced dispersion. Inactivation of
mucR
impaired biofilm dispersion in response to NO and glutamate, whereas inactivation of
nbdA
only impaired biofilm dispersion upon exposure to NO. A specific role of NbdA in NO-induced dispersion was supported by increased PDE activity, resulting in decreased c-di-GMP levels in biofilms expressing
nbdA
upon exposure to NO, a response that was absent in the Δ
nbdA
strain. Moreover, increased PDE activity was mainly due to a transcriptional activation of
nbdA
upon addition of NO. Biochemical analyses of recombinant protein variants lacking the membrane-anchored MHYT domain support NbdA being an active PDE. In contrast, MucR displayed both diguanylate cyclase and PDE activity
in vitro
, which seemed regulated in a growth-dependent manner
in vivo
. This is the first description of a PDE specifically involved in NO-induced biofilm dispersion in
P. aeruginosa
.
Publisher
American Society for Microbiology
Subject
Molecular Biology,Microbiology
Cited by
132 articles.
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