Affiliation:
1. Department of Microbiology and Immunology, Loyola University Medical Center, Maywood, Illinois
Abstract
ABSTRACT
Bacteria produce different types of biofilms under distinct environmental conditions.
Vibrio fischeri
has the capacity to produce at least two distinct types of biofilms, one that relies on the symbiosis polysaccharide Syp and another that depends upon cellulose. A key regulator of biofilm formation in bacteria is the intracellular signaling molecule cyclic diguanylate (c-di-GMP). In this study, we focused on a predicted c-di-GMP phosphodiesterase encoded by the gene
binA
, located directly downstream of
syp
, a cluster of 18 genes critical for biofilm formation and the initiation of symbiotic colonization of the squid
Euprymna scolopes
. Disruption or deletion of
binA
increased biofilm formation in culture and led to increased binding of Congo red and calcofluor, which are indicators of cellulose production. Using random transposon mutagenesis, we determined that the phenotypes of the Δ
binA
mutant strain could be disrupted by insertions in genes in the bacterial cellulose biosynthesis cluster (
bcs
), suggesting that cellulose production is negatively regulated by BinA. Replacement of critical amino acids within the conserved EAL residues of the EAL domain disrupted BinA activity, and deletion of
binA
increased c-di-GMP levels in the cell. Together, these data support the hypotheses that BinA functions as a phosphodiesterase and that c-di-GMP activates cellulose biosynthesis. Finally, overexpression of the
syp
regulator
sypG
induced
binA
expression. Thus, this work reveals a mechanism by which
V. fischeri
inhibits cellulose-dependent biofilm formation and suggests that the production of two different polysaccharides may be coordinated through the action of the cellulose inhibitor BinA.
Publisher
American Society for Microbiology
Subject
Molecular Biology,Microbiology
Cited by
51 articles.
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