Role of MrkJ, a phosphodiesterase, in type 3 fimbrial expression and biofilm formation in Klebsiella pneumoniae.
Klebsiella pneumoniae is an opportunistic pathogen that has been shown to adhere to human extracellular matrices using the type 3 fimbriae. Introduction of plasmids carrying genes known to alter intracellular cyclic-di-GMP pools in Vibrio parahaemolyticus revealed that these genes also altered type 3 fimbrial surface expression in K. pneumoniae. Immediately adjacent to the type 3 fimbrial gene cluster is a gene, mrkJ, that is related to a family of bacterial genes encoding phosphodiesterases. We identify here a role for MrkJ, a functional phosphodiesterase exhibiting homology to EAL domain-containing proteins, in controlling type 3 fimbria production and biofilm formation in K. pneumoniae. Deletion of mrkJ resulted in an increase in type 3 fimbria production and biofilm formation as a result of the accumulation of intracellular cyclic-di-GMP. This gene was shown to encode a functional phosphodiesterase via restoration of motility in a V. parahaemolyticus strain previously shown to accumulate cyclic-di-GMP and in vitro using phosphodiesterase activity assays. The effect of the mrkJ mutation on type 3 fimbrial expression was shown to be at the level of mrkA gene transcription by using quantitative reverse transcription-PCR. These results reveal a previously unknown role for cyclic-di-GMP in type 3 fimbrial production.
Department of Microbiology, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, Iowa 52242, USA.
Jeremiah G
JG
Johnson
Steven
S
Clegg
D018441:Biofilms / Q000254:growth & development*; D029968:Escherichia coli Proteins; D036781:Fimbriae Proteins / Q000235:genetics / Q000378:metabolism*; D015964:Gene Expression Regulation, Bacterial / Q000502:physiology*; D015971:Gene Expression Regulation, Enzymologic / Q000502:physiology*; D007711:Klebsiella pneumoniae / Q000201:enzymology* / Q000235:genetics / Q000502:physiology; D005810:Multigene Family; D009154:Mutation; D010727:Phosphoric Diester Hydrolases / Q000235:genetics / Q000378:metabolism*; D019761:Phosphorus-Oxygen Lyases / Q000378:metabolism; D010957:Plasmids; D014158:Transcription, Genetic
D029968:Escherichia coli Proteins; D036781:Fimbriae Proteins; D010727:Phosphoric Diester Hydrolases; D019761:Phosphorus-Oxygen Lyases; C060720:diguanylate cyclase