title: The CRP/FNR family protein Bcam1349 is a c-di-GMP effector that regulates biofilm formation in the respiratory pathogen Burkholderia cenocepacia.
abstract: Burkholderia cenocepacia is an opportunistic respiratory pathogen that can cause severe infections in immune-compromised individuals and is associated with poor prognosis for patients suffering from cystic fibrosis. The second messenger cyclic diguanosine monophosphate (c-di-GMP) has been shown to control a wide range of functions in bacteria, but little is known about these regulatory mechanisms in B. cenocepacia. Here we investigated the role that c-di-GMP plays in the regulation of biofilm formation and virulence in B. cenocepacia. Elevated intracellular levels of c-di-GMP promoted wrinkly colony, pellicle and biofilm formation in B. cenocepacia. A screen for transposon mutants unable to respond to elevated levels of c-di-GMP led to the identification of the mutant bcam1349 that did not display increased biofilm and pellicle formation with excessive c-di-GMP levels, and displayed a biofilm defect with physiological c-di-GMP levels. The bcam1349 gene is predicted to encode a transcriptional regulator of the CRP/FNR superfamily. Analyses of purified Bcam1349 protein and truncations demonstrated that it binds c-di-GMP in vitro. The Bcam1349 protein was shown to regulate the production of a number of components, including cellulose and fimbriae. It was demonstrated that the Bcam1349 protein binds to the promoter region of the cellulose synthase genes, and that this binding is enhanced by the presence of c-di-GMP. The bcam1349 mutant showed reduced virulence in a Galleria mellonella wax moth larvae infection model. Taken together, these findings suggest that the Bcam1349 protein is a transcriptional regulator that binds c-di-GMP and regulates biofilm formation and virulence in B. cenocepacia in response to the level of c-di-GMP.
authors: Department of International Health, Immunology and Microbiology, Faculty of Health Sciences, University of Copenhagen, Copenhagen, Denmark.
authors: Mustafa
authors: M
authors: Fazli
authors: Aileen
authors: A
authors: O'Connell
authors: Martin
authors: M
authors: Nilsson
authors: Karsten
authors: K
authors: Niehaus
authors: J Maxwell
authors: JM
authors: Dow
authors: Michael
authors: M
authors: Givskov
authors: Robert P
authors: RP
authors: Ryan
authors: Tim
authors: T
authors: Tolker-Nielsen
mesh_terms: D000818:Animals; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D018441:Biofilms; D019121:Burkholderia Infections / Q000382:microbiology*; D057508:Burkholderia cenocepacia / Q000235:genetics / Q000472:pathogenicity / Q000502:physiology*; D006152:Cyclic GMP / Q000031:analogs & derivatives* / Q000378:metabolism; D015964:Gene Expression Regulation, Bacterial; D006801:Humans; D009036:Moths; D005810:Multigene Family; D011401:Promoter Regions, Genetic; D011485:Protein Binding; D012141:Respiratory Tract Infections / Q000382:microbiology*; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*; D014774:Virulence
chemical_list: D001426:Bacterial Proteins; D014157:Transcription Factors; C062025:bis(3',5')-cyclic diguanylic acid; D006152:Cyclic GMP