Fur regulation of the capsular polysaccharide biosynthesis and iron-acquisition systems in Klebsiella pneumoniae CG43.
The ferric uptake regulator Fur has been reported to repress the expression of rmpA, a regulatory gene for the mucoid phenotype, leading to decreased capsular polysaccharide (CPS) biosynthesis in Klebsiella pneumoniae CG43. Here, quantitative real-time PCR (qRT-PCR) analyses and electrophoretic mobility shift assays showed that Fur also repressed the expression of the CPS regulatory genes rmpA2 and rcsA. Interestingly, deletion of rmpA or rcsA but not rmpA2 from the Δfur strain was able to suppress the deletion effect of Fur. The availability of extracellular iron affected the amount of CPS, suggesting that Fur regulates CPS biosynthesis in an Fe(II)-dependent manner. Increased production of siderophores was observed in the Δfur strain, suggesting that uptake of extracellular iron in K. pneumoniae is regulated by Fur. Fur titration assays and qRT-PCR analyses demonstrated that at least six of the eight putative iron-acquisition systems, identified by a blast search in the contig database of K. pneumoniae CG43, were directly repressed by Fur. We conclude that Fur has a dual role in the regulation of CPS biosynthesis and iron acquisition in K. pneumoniae.
School of Chinese Medicine, China Medical University, Taichung, 40402, Taiwan, ROC.
Ching-Ting
CT
Lin
Department of Biological Science and Technology, National Chiao Tung University, Hsin Chu 30068, Taiwan, ROC.
Chien-Chen
CC
Wu
School of Chinese Medicine, China Medical University, Taichung, 40402, Taiwan, ROC.
Yu-Sheng
YS
Chen
Department of Microbiology and Immunology, Chung-Shan Medical University, Taichung 40201, Taiwan, ROC.
Yi-Chyi
YC
Lai
School of Chinese Medicine, China Medical University, Taichung, 40402, Taiwan, ROC.
Chia
C
Chi
School of Chinese Medicine, China Medical University, Taichung, 40402, Taiwan, ROC.
Jing-Ciao
JC
Lin
Research Institute of Biotechnology, Hungkuang University, Taichung 43302, Taiwan, ROC.
Yeh
Y
Chen
Department of Biological Science and Technology, National Chiao Tung University, Hsin Chu 30068, Taiwan, ROC.
Hwei-Ling
HL
Peng
D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D017353:Gene Deletion; D015964:Gene Expression Regulation, Bacterial; D007501:Iron / Q000378:metabolism*; D007711:Klebsiella pneumoniae / Q000235:genetics* / Q000378:metabolism; D009154:Mutation; D011135:Polysaccharides, Bacterial / Q000096:biosynthesis*; D012329:RNA, Bacterial / Q000235:genetics; D012097:Repressor Proteins / Q000235:genetics / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D017262:Siderophores / Q000096:biosynthesis; D014157:Transcription Factors / Q000378:metabolism
D001426:Bacterial Proteins; D011135:Polysaccharides, Bacterial; D012329:RNA, Bacterial; D012097:Repressor Proteins; C512267:RmpA protein, Klebsiella pneumoniae; C082298:RmpA2 protein, Klebsiella pneumoniae; D017262:Siderophores; D014157:Transcription Factors; C068477:ferric uptake regulating proteins, bacterial; D007501:Iron