title: Characterization of a novel two-component system response regulator involved in biofilm formation and a low-iron response of Burkholderia pseudomallei.
abstract: Two-component systems (TCSs) regulate an adaptive response to environmental conditions, leading to changes in bacterial cellular processes. In this study, we identified a novel TCS response regulator gene, designated as bfmR (biofilm formation-associated regulator) that regulates biofilm formation by Burkholderia pseudomallei (Bp). An insertion mutant of the Bp bfmR gene resulted in a significant decrease in expression of fimbriae chaperone-usher assembly genes (BPSL2O28 and BPSL22 7), leading to suppression of assembly of fimbriae on the cell surface and reduced biofilm formation. The defective phenotypes of the mutant strain were restored by introducing a complementing plasmid having an intact bfmR gene. Using RT-PCR analyses, we found that bfmR gene expression was upregulated under low-iron growth conditions. In addition, the bfmR mutant strain showed retarded growth in low-iron medium and in phagocytic cells compared to the wild-type strain. These results indicate that bfmR is a novel positive regulator for controlling assembly of fimbriae and biofilm formation, and is upregulated under low-iron conditions.
authors.forename: Sompong
authors.initials: S
authors.lastname: Tabunhan
authors.forename: Surasakdi
authors.initials: S
authors.lastname: Wongratanacheewin
authors.forename: Suwin
authors.initials: S
authors.lastname: Wongwajana
authors.forename: Tariva Umka
authors.initials: TU
authors.lastname: Welbat
authors.forename: Kiatichai
authors.initials: K
authors.lastname: Faksri
authors.forename: Wises
authors.initials: W
authors.lastname: Namwat
mesh_terms: D000818:Animals; D018441:Biofilms / Q000254:growth & development*; D016957:Burkholderia pseudomallei / Q000235:genetics* / Q000254:growth & development*; D002460:Cell Line; D015536:Down-Regulation / Q000235:genetics; D010861:Fimbriae, Bacterial / Q000187:drug effects; D007501:Iron / Q000494:pharmacology; D051379:Mice; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015854:Up-Regulation / Q000235:genetics
chemical_list: D007501:Iron