title: FlrA Represses Transcription of the Biofilm-Associated bpfA Operon in Shewanella putrefaciens.
abstract: Manipulation of biofilm formation in Shewanella is beneficial for application to industrial and environmental biotechnology. BpfA is an adhesin largely responsible for biofilm formation in many Shewanella species. However, the mechanism underlying BpfA production and the resulting biofilm remains vaguely understood. We previously described the finding that BpfA expression is enhanced by DosD, an oxygen-stimulated diguanylate cyclase, under aerobic growth. In the present work, we identify FlrA as a critical transcription regulator of the bpfA operon in Shewanella putrefaciens CN32 by transposon mutagenesis. FlrA acted as a repressor of the operon promoter by binding to two boxes overlapping the -10 and -35 sites recognized by σ70DosD regulation of the expression of the bpfA operon was mediated by FlrA, and cyclic diguanylic acid (c-di-GMP) abolished FlrA binding to the operon promoter. We also demonstrate that FlhG, an accessory protein for flagellum synthesis, antagonized FlrA repression of the expression of the bpfA operon. Collectively, this work demonstrates that FlrA acts as a central mediator in the signaling pathway from c-di-GMP to BpfA-associated biofilm formation in S. putrefaciens CN32.
  
  
  
  Motility and biofilm are mutually exclusive lifestyles, shifts between which are under the strict regulation of bacteria attempting to adapt to the fluctuation of diverse environmental conditions. The FlrA protein in many bacteria is known to control motility as a master regulator of flagellum synthesis. This work elucidates its effect on biofilm formation by controlling the expression of the adhesin BpfA in S. putrefaciens CN32 in response to c-di-GMP. Therefore, FlrA plays a dual role in controlling motility and biofilm formation in S. putrefaciens CN32. The cooccurrence of flrA, bpfA, and the FlrA box in the promoter region of the bpfA operon in diverse Shewanella strains suggests that bpfA is a common mechanism that controls biofilm formation in this bacterial species.
authors.affiliation: School of Life Sciences, Anhui University, Hefei, China chengyy@ahu.edu.cn.|Anhui Provincial Engineering Technology Research Center of Microorganisms and Biocatalysis, Anhui University, Hefei, China.
authors.forename: Yuan-Yuan
authors.initials: YY
authors.lastname: Cheng
authors.affiliation: School of Resources and Environment, Anhui University, Hefei, China.
authors.forename: Chao
authors.initials: C
authors.lastname: Wu
authors.affiliation: School of Life Sciences, Anhui University, Hefei, China.
authors.forename: Jia-Yi
authors.initials: JY
authors.lastname: Wu
authors.affiliation: School of Life Sciences, Anhui University, Hefei, China.
authors.forename: Hui-Ling
authors.initials: HL
authors.lastname: Jia
authors.affiliation: Anhui Provincial Engineering Technology Research Center of Microorganisms and Biocatalysis, Anhui University, Hefei, China.
authors.forename: Ming-Yu
authors.initials: MY
authors.lastname: Wang
authors.affiliation: School of Life Sciences, Anhui University, Hefei, China.
authors.forename: Huan-Yu
authors.initials: HY
authors.lastname: Wang
authors.affiliation: School of Life Sciences, Anhui University, Hefei, China.
authors.forename: Si-Min
authors.initials: SM
authors.lastname: Zou
authors.affiliation: School of Life Sciences, Anhui University, Hefei, China.
authors.forename: Rui-Rui
authors.initials: RR
authors.lastname: Sun
authors.affiliation: School of Life Sciences, Anhui University, Hefei, China.|Anhui Provincial Engineering Technology Research Center of Microorganisms and Biocatalysis, Anhui University, Hefei, China.
authors.forename: Rong
authors.initials: R
authors.lastname: Jia
authors.affiliation: School of Life Sciences, Anhui University, Hefei, China.|Anhui Provincial Engineering Technology Research Center of Microorganisms and Biocatalysis, Anhui University, Hefei, China.
authors.forename: Ya-Zhong
authors.initials: YZ
authors.lastname: Xiao
mesh_terms: D018829:Adhesins, Bacterial / Q000235:genetics* / Q000378:metabolism; D001426:Bacterial Proteins / Q000235:genetics; D001483:Base Sequence; D018441:Biofilms / Q000254:growth & development*; D006152:Cyclic GMP / Q000031:analogs & derivatives / Q000494:pharmacology; D005407:Flagella / Q000378:metabolism; D015964:Gene Expression Regulation, Bacterial / Q000235:genetics; D011401:Promoter Regions, Genetic / Q000235:genetics; D012097:Repressor Proteins / Q000235:genetics*; D020614:Shewanella putrefaciens / Q000235:genetics / Q000378:metabolism*; D014158:Transcription, Genetic / Q000235:genetics*
chemical_list: D018829:Adhesins, Bacterial; D001426:Bacterial Proteins; D012097:Repressor Proteins; C062025:bis(3',5')-cyclic diguanylic acid; D006152:Cyclic GMP
keywords: FlrA; Shewanella; biofilm; cyclic di-GMP; transcriptional factor