title: Fur-dependent MrkHI regulation of type 3 fimbriae in Klebsiella pneumoniae CG43.
abstract: Type 3 fimbriae play a crucial role in Klebsiella pneumoniae biofilm formation, but the mechanism of the regulation of the type 3 fimbrial operon is largely unknown. In K. pneumoniae CG43, three regulatory genes, mrkH, mrkI and mrkJ, are located downstream of the type 3 fimbrial genes mrkABCDF. The production of the major pilin MrkA is abolished by the deletion of mrkH or mrkI but slightly increased by the deletion of mrkJ. Additionally, quantitative RT-PCR and a promoter-reporter assay of mrkHI verified that the transcription of mrkHI was activated by MrkI, suggesting autoactivation of mrkHI transcription. In addition, sequence analysis of the mrkH promoter region revealed a putative ferric uptake regulator (Fur) box. Deletion of fur decreased the transcription of mrkH, mrkI and mrkA. The expression of type 3 fimbriae and bacterial biofilm formation were also reduced by the deletion of fur. Moreover, a recombinant Fur was found to be able to bind both promoters, with higher affinity for P(mrkH) than P(mrkA), implying that Fur controls type 3 fimbriae expression via MrkHI. We also proved that iron availability can influence type 3 fimbriae activity.
authors.affiliation: Department of Biological Science and Technology, National Chiao Tung University, Hsin Chu, Taiwan, ROC.
authors.forename: Chien-Chen
authors.initials: CC
authors.lastname: Wu
authors.affiliation: School of Chinese Medicine, China Medical University, Taichung, Taiwan, ROC.
authors.forename: Ching-Ting
authors.initials: CT
authors.lastname: Lin
authors.affiliation: Department of Biological Science and Technology, National Chiao Tung University, Hsin Chu, Taiwan, ROC.
authors.forename: Wei-Yun
authors.initials: WY
authors.lastname: Cheng
authors.affiliation: Institute of Molecular Medicine and Bioengineering, National Chiao Tung University, Hsin Chu, Taiwan, ROC.
authors.forename: Ching-Jou
authors.initials: CJ
authors.lastname: Huang
authors.affiliation: Department of Biological Science and Technology, National Chiao Tung University, Hsin Chu, Taiwan, ROC.
authors.forename: Zhe-Chong
authors.initials: ZC
authors.lastname: Wang
authors.affiliation: Institute of Molecular Medicine and Bioengineering, National Chiao Tung University, Hsin Chu, Taiwan, ROC.|Department of Biological Science and Technology, National Chiao Tung University, Hsin Chu, Taiwan, ROC.
authors.forename: Hwei-Ling
authors.initials: HL
authors.lastname: Peng
mesh_terms: D018829:Adhesins, Bacterial / Q000235:genetics / Q000378:metabolism*; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D018441:Biofilms / Q000254:growth & development; D036781:Fimbriae Proteins / Q000235:genetics / Q000378:metabolism*; D010861:Fimbriae, Bacterial / Q000502:physiology*; D017353:Gene Deletion; D015964:Gene Expression Regulation, Bacterial; D005816:Genetic Complementation Test; D007501:Iron / Q000378:metabolism; D007711:Klebsiella pneumoniae / Q000235:genetics* / Q000378:metabolism / Q000502:physiology; D009876:Operon; D011401:Promoter Regions, Genetic; D012097:Repressor Proteins / Q000235:genetics / Q000378:metabolism*; D014158:Transcription, Genetic; D015533:Transcriptional Activation
chemical_list: D018829:Adhesins, Bacterial; D001426:Bacterial Proteins; C058768:Klebsiella pneumoniae type 3 fimbrial adhesin; D012097:Repressor Proteins; C068477:ferric uptake regulating proteins, bacterial; D036781:Fimbriae Proteins; D007501:Iron