A cyclic AMP receptor protein-regulated cell-cell communication system mediates expression of a FecA homologue in Stenotrophomonas maltophilia.
Stenotrophomonas maltophilia WR-C possesses an rpf/diffusible signal factor (DSF) cell-cell communication system. It produces cis-Delta2-11-methyl-dodecenoic acid, a DSF, and seven structural derivatives, which require rpfF and rpfB for synthesis. Acquisition of iron from the environment is important for bacterial growth as well as the expression of virulence genes. We identified a gene homologous to fecA, which encodes a ferric citrate receptor that transports exogenous siderophore ferric citrate from the environment into the bacterial periplasm. Western blot analysis with anti-FecA-His(6) antibody showed that the FecA homologue was induced in the iron-depleted medium supplemented with a low concentration of ferric citrate. Deletion of rpfF or rpfB resulted in reduced FecA expression compared to the wild type. Synthetic DSF restored FecA expression by the DeltarpfF mutant to the wild-type level. Reverse transcription-PCR showed that the fecA transcript was decreased in the DeltarpfF mutant compared to the wild type. These data suggest that DSF affected the level of fecA mRNA. Transposon inactivation of crp, which encodes cyclic AMP (cAMP) receptor protein (CRP) resulted in reduced FecA expression and rpfF transcript level. Putative CRP binding sites were located upstream of the rpfF promoter, indicating that the effect of CRP on FecA is through the rpf/DSF pathway and by directly controlling rpfF. We propose that CRP may serve as a checkpoint for iron uptake, protease activity, and hemolysis in response to environmental changes such as changes in concentrations of glucose, cAMP, iron, or DSF.
Huang
Tzu-Pi
TP
Department of Food Microbiology and Toxicology, University of Wisconsin-Madison, Madison, WI 53706, USA.
Wong
Amy C Lee
AC
D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D001483:Base Sequence; D001692:Biological Transport; D002373:Cyclic AMP Receptor Protein / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D004251:DNA Transposable Elements; D029968:Escherichia coli Proteins / Q000737:chemistry; D005290:Ferric Compounds / Q000378:metabolism*; D015964:Gene Expression Regulation, Bacterial; D008969:Molecular Sequence Data; D016254:Mutagenesis, Insertional; D011956:Receptors, Cell Surface / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D017422:Sequence Analysis, DNA; D015398:Signal Transduction; D020615:Stenotrophomonas maltophilia / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*
D001426:Bacterial Proteins; D002373:Cyclic AMP Receptor Protein; D004251:DNA Transposable Elements; D029968:Escherichia coli Proteins; C028589:FecA protein, E coli; D005290:Ferric Compounds; D011956:Receptors, Cell Surface; C025314:ferric citrate