title: FimK regulation on the expression of type 1 fimbriae in Klebsiella pneumoniae CG43S3.
abstract: Klebsiella pneumoniae CG43, a heavy encapsulated liver abscess isolate, mainly expresses type 3 fimbriae. Type 1 fimbriae expression was only apparent in CG43S3ΔmrkA (the type 3 fimbriae-deficient strain). The expression of type 1 fimbriae in CG43S3ΔmrkA was reduced by deleting the fimK gene, but was unaffected by removing the 3' end of fimK encoding the C-terminal EIL domain (EILfimK). Quantitative RT-PCR and promoter activity analysis showed that the putative DNA-binding region at the N terminus, but not the C-terminal EIL domain, of FimK positively affects transcription of the type 1 fimbrial major subunit, fimA. An electrophoretic mobility shift assay demonstrated that the recombinant FimK could specifically bind to fimS, which is located upstream of fimA and contains a vegetative promoter for the fim operon, also reflecting possible transcriptional regulation. EILfimK was shown to encode a functional phosphodiesterase (PDE) via enhancing motility in Escherichia coli JM109 and in vitro using PDE activity assays. Moreover, EILfimK exhibited higher PDE activity than FimK, implying that the N-terminal DNA-binding domain may negatively affect the PDE activity of FimK. FimA expression was detected in CG43S3 expressing EILfimK or AILfimK, suggesting that FimA expression is not directly influenced by the c-di-GMP level. In summary, FimK influences type 1 fimbriation by binding to fimS at the N-terminal domain, and thereafter, the altered protein structure may activate C-terminal PDE activity to reduce the intracellular c-di-GMP level.
authors.affiliation: Department of Biological Science and Technology, National Chiao Tung University, Hsin Chu, Taiwan, Republic of China.
authors.forename: Zhe-Chong
authors.initials: ZC
authors.lastname: Wang
authors.affiliation: Institute of Molecular Medicine and Bioengineering, School of Biological Science and Technology, National Chiao Tung University, Hsin Chu, Taiwan, Republic of China.
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, Republic of China.
authors.forename: Ying-Jung
authors.initials: YJ
authors.lastname: Huang
authors.affiliation: Department of Biological Science and Technology, National Chiao Tung University, Hsin Chu, Taiwan, Republic of China.
authors.forename: Chien-Chen
authors.initials: CC
authors.lastname: Wu
authors.affiliation: Institute of Molecular Medicine and Bioengineering, School of Biological Science and Technology, National Chiao Tung University, Hsin Chu, Taiwan, Republic of China.|Department of Biological Science and Technology, National Chiao Tung University, Hsin Chu, Taiwan, Republic of China.
authors.forename: Hwei-Ling
authors.initials: HL
authors.lastname: Peng
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D006152:Cyclic GMP / Q000031:analogs & derivatives / Q000378:metabolism; D036781:Fimbriae Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D010861:Fimbriae, Bacterial / Q000235:genetics / Q000378:metabolism*; D015964:Gene Expression Regulation, Bacterial; D006801:Humans; D007711:Klebsiella pneumoniae / Q000235:genetics / Q000378:metabolism* / Q000502:physiology; D009876:Operon; D010727:Phosphoric Diester Hydrolases / Q000235:genetics / Q000378:metabolism*
chemical_list: D001426:Bacterial Proteins; D036781:Fimbriae Proteins; C062025:bis(3',5')-cyclic diguanylic acid; D010727:Phosphoric Diester Hydrolases; D006152:Cyclic GMP