Dataset Information

Identification of FleQ from Pseudomonas aeruginosa as a c-di-GMP-responsive transcription factor.

ABSTRACT: High levels of the intracellular signalling molecule cyclic diguanylate (c-di-GMP) supress motility and activate exopolysaccharide (EPS) production in a variety of bacterial species. In many bacteria part of the effect of c-di-GMP is on gene expression, but the mechanism involved is not known for any species. We have identified the protein FleQ as a c-di-GMP-responsive transcriptional regulator in Pseudomonas aeruginosa. FleQ is known to activate expression of flagella biosynthesis genes. Here we show that it also represses transcription of genes including the pel operon involved in EPS biosynthesis, and that this repression is relieved by c-di-GMP. Our in vivo data indicate that FleQ represses pel transcription and that pel transcription is not repressed when intracellular c-di-GMP levels are high. FleN, a known antiactivator of FleQ also participates in control of pel expression. In in vitro experiments we found that FleQ binds to pel promoter DNA and that this binding is inhibited by c-di-GMP. FleQ binds radiolabelled c-di-GMP in vitro. FleQ does not have amino acid motifs that resemble previously defined c-di-GMP binding domains. Our results show that FleQ is a new type of c-di-GMP binding protein that controls the transcriptional regulation of EPS biosynthesis genes in P. aeruginosa.

SUBMITTER: Hickman JW

PROVIDER: S-EPMC2612001 | biostudies-literature | 2008 Jul

REPOSITORIES: biostudies-literature

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Identification of FleQ from Pseudomonas aeruginosa as a c-di-GMP-responsive transcription factor.

Hickman Jason W JW Harwood Caroline S CS

Molecular microbiology 20080701 2

High levels of the intracellular signalling molecule cyclic diguanylate (c-di-GMP) supress motility and activate exopolysaccharide (EPS) production in a variety of bacterial species. In many bacteria part of the effect of c-di-GMP is on gene expression, but the mechanism involved is not known for any species. We have identified the protein FleQ as a c-di-GMP-responsive transcriptional regulator in Pseudomonas aeruginosa. FleQ is known to activate expression of flagella biosynthesis genes. Here w ...[more]

PMID: 18485075

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Project description:The bacterial second messenger cyclic diguanylate (c-di-GMP) modulates plankton-to-biofilm lifestyle transition of Pseudomonas species through its transcriptional regulatory effector FleQ. FleQ regulates transcription of biofilm- and flagellum-related genes in response to c-di-GMP. Through transcriptomic analysis and FleQ-DNA binding assay, this study identified five new target genes of c-di-GMP/FleQ in P. putida, including PP_0681, PP_0788, PP_4519 (lapE), PP_5222 (cyaA), and PP_5586 Except lapE encoding an outer membrane pore protein and cyaA encoding an adenylate cyclase, the functions of the other three genes encoding hypothetical proteins remain unknown. FleQ and c-di-GMP coordinately inhibit transcription of PP_0788 and cyaA and promote transcription of PP_0681, lapE, and PP_5586 Both in vitro and in vivo assays show that FleQ binds directly to promoters of the five genes. Further analyses confirm that LapE plays a central role of in the secretion of adhesin LapA and that c-di-GMP/FleQ increases lapE transcription, thereby promoting adhesin secretion and biofilm formation. The adenylate cyclase CyaA is responsible for synthesis of another second messenger, cyclic AMP (cAMP). FleQ and c-di-GMP coordinate to decrease the content of cAMP, suggesting that c-di-GMP and FleQ coregulate cAMP by modulating cyaA expression. Overall, this study adds five new members to the c-di-GMP/FleQ-regulated gene family and reveals the role of c-di-GMP/FleQ in LapA secretion and cAMP synthesis regulation in P. putida IMPORTANCE c-di-GMP/FleQ promotes the plankton-to-biofilm lifestyle transition at the transcriptional level via FleQ in Pseudomonas species. Identification of new target genes directly regulated by c-di-GMP/FleQ helps to broaden the knowledge of c-di-GMP/FleQ-mediated transcriptional regulation. Regulation of lapE by c-di-GMP/FleQ guarantees highly efficient LapA secretion and biofilm formation. The mechanism of negative correlation between c-di-GMP and cAMP in both P. putida and P. aeruginosa remains unknown. Our result concerning transcriptional inhibition of cyaA by c-di-GMP/FleQ reveals the mechanism underlying the decrease of cAMP content by c-di-GMP in P. putida.

Dataset Information

Identification of FleQ from Pseudomonas aeruginosa as a c-di-GMP-responsive transcription factor.

Publications

Identification of FleQ from Pseudomonas aeruginosa as a c-di-GMP-responsive transcription factor.

Similar Datasets

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