Open AccessThe Cyclic AMP Receptor Protein Modulates Colonial Morphology in Vibrio cholerae
Author(s) -
Weili Liang,
Alcino J. Silva,
Jorge A. Benítez
Publication year - 2007
Publication title -
applied and environmental microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.552
H-Index - 324
eISSN - 1070-6291
pISSN - 0099-2240
DOI - 10.1128/aem.01564-07
Subject(s) - vibrio cholerae , mutant , quorum sensing , biology , microbiology and biotechnology , biofilm , camp receptor protein , activator (genetics) , complementation , wild type , ectopic expression , receptor , gene , gene expression , biochemistry , genetics , bacteria , promoter
Inactivation of the quorum-sensing regulator HapR causesVibrio cholerae El Tor biotype strain C7258 to adopt a rugose colonial morphology that correlates with enhanced biofilm formation.V. cholerae mutants lacking the cyclic AMP (cAMP) receptor protein (CRP) produce very little HapR, which results in elevated expression ofVibrio exopolysaccharide (vps ) genes and biofilm compared to the wild type. However, Δcrp mutants still exhibited smooth colonial morphology and expressed reduced levels ofvps genes compared to isogenichapR mutants. In this study we demonstrate that deletion ofcrp andcya (adenylate cyclase) converts a rugose ΔhapR mutant to a smooth one. The smooth ΔhapR Δcrp and ΔhapR Δcya double mutants could be converted back to rugose by complementation withcrp andcya , respectively. CRP was found to enhance the expression of VpsR, a strong activator ofvps expression, but to diminish transcription of VpsT. Ectopic expression of VpsR in smooth ΔhapR Δcrp and ΔhapR Δcya double mutants restored rugose colonial morphology. Lowering intracellular cAMP levels in a ΔhapR mutant by the addition of glucose diminished VpsR expression and colonial rugosity. On the basis of our results, we propose a model for the regulatory input of CRP on exopolysaccharide biosynthesis.