Title: Fur-dependent MrkHI regulation of type 3 fimbriae in Klebsiella pneumoniae CG43
Authors: Wu, Chien-Chen
Lin, Ching-Ting
Cheng, Wei-Yun
Huang, Ching-Jou
Wang, Zhe-Chong
Peng, Hwei-Ling
Department of Biological Science and Technology
Institute of Molecular Medicine and Bioengineering
Issue Date: 1-Apr-2012
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.
URI: http://hdl.handle.net/11536/16051
ISSN: 1350-0872
Volume: 158
End Page: 1045
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