Biofilm formation and dispersal under the influence of the global regulator CsrA of Escherichia coli.
The predominant mode of growth of bacteria in the environment is within sessile, matrix-enclosed communities known as biofilms. Biofilms often complicate chronic and difficult-to-treat infections by protecting bacteria from the immune system, decreasing antibiotic efficacy, and dispersing planktonic cells to distant body sites. While the biology of bacterial biofilms has become a major focus of microbial research, the regulatory mechanisms of biofilm development remain poorly defined and those of dispersal are unknown. Here we establish that the RNA binding global regulatory protein CsrA (carbon storage regulator) of Escherichia coli K-12 serves as both a repressor of biofilm formation and an activator of biofilm dispersal under a variety of culture conditions. Ectopic expression of the E. coli K-12 csrA gene repressed biofilm formation by related bacterial pathogens. A csrA knockout mutation enhanced biofilm formation in E. coli strains that were defective for extracellular, surface, or regulatory factors previously implicated in biofilm formation. In contrast, this csrA mutation did not affect biofilm formation by a glgA (glycogen synthase) knockout mutant. Complementation studies with glg genes provided further genetic evidence that the effects of CsrA on biofilm formation are mediated largely through the regulation of intracellular glycogen biosynthesis and catabolism. Finally, the expression of a chromosomally encoded csrA'-'lacZ translational fusion was dynamically regulated during biofilm formation in a pattern consistent with its role as a repressor. We propose that global regulation of central carbon flux by CsrA is an extremely important feature of E. coli biofilm development.
Jackson
Debra W
DW
Department of Molecular Biology and Immunology, University of North Texas Health Science Center at Fort Worth, Fort Worth, Texas 76107-2699, USA.
Suzuki
Kazushi
K
Oakford
Lawrence
L
Simecka
Jerry W
JW
Hart
Mark E
ME
Romeo
Tony
T
D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D018441:Biofilms / Q000254:growth & development*; D004926:Escherichia coli / Q000235:genetics* / Q000254:growth & development*; D029968:Escherichia coli Proteins; D015964:Gene Expression Regulation, Bacterial; D017930:Genes, Reporter; D006003:Glycogen / Q000378:metabolism; D007763:Lac Operon; D009154:Mutation; D012323:RNA Processing, Post-Transcriptional; D062085:RNA, Long Noncoding; D022661:RNA, Untranslated / Q000235:genetics; D016601:RNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D011994:Recombinant Proteins / Q000378:metabolism; D012097:Repressor Proteins
D001426:Bacterial Proteins; C093587:CsrA protein, E coli; C107123:CsrB RNA, E coli; D029968:Escherichia coli Proteins; D062085:RNA, Long Noncoding; D022661:RNA, Untranslated; D016601:RNA-Binding Proteins; D011994:Recombinant Proteins; D012097:Repressor Proteins; D006003:Glycogen