title: SOS involvement in stress-inducible biofilm formation.
abstract: Bacterial biofilm formation can be induced by antimicrobial and DNA damage agents. These agents trigger the SOS response, in which SOS sensor RecA stimulates auto-cleavage of repressor LexA. These observations lead to a hypothesis of a connection between stress-inducible biofilm formation and the RecA-LexA interplay. To test this hypothesis, three biofilm assays were conducted, viz. the standard 96-well assay, confocal laser scanning microscopy, and the newly developed biofilm-on-paper assay. It was found that biofilm stimulation by the DNA replication inhibitor hydroxyurea was dependent on RecA and appeared repressed by the non-cleavable LexA of Pseudomonas aeruginosa. Surprisingly, deletion of lexA led to reduction of both normal and stress-inducible biofilm formation, suggesting that the wild-type LexA contributes to biofilm formation. The decreases was not the result of poor growth of the mutants. These results suggest SOS involvement in hydroxyurea-inducible biofilm formation. In addition, with the paper biofilm assay, it was found that degradation of the biofilm matrix DNA by DNase I appeared to render the biofilms susceptible to the replication inhibitor. The puzzling questions concerning the roles of LexA in DNA release in the biofilm context are discussed.
authors.affiliation: Department of Biology, The University of Texas at San Antonio, San Antonio, TX 78249, USA.
authors.forename: H
authors.initials: H
authors.lastname: Gotoh
authors.forename: N
authors.initials: N
authors.lastname: Kasaraneni
authors.forename: N
authors.initials: N
authors.lastname: Devineni
authors.forename: S F
authors.initials: SF
authors.lastname: Dallo
authors.forename: T
authors.initials: T
authors.lastname: Weitao
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics; D018441:Biofilms / Q000187:drug effects / Q000254:growth & development*; D006918:Hydroxyurea / Q000494:pharmacology; D018613:Microscopy, Confocal; D009154:Mutation; D019384:Nucleic Acid Synthesis Inhibitors / Q000494:pharmacology; D011550:Pseudomonas aeruginosa / Q000187:drug effects / Q000235:genetics* / Q000254:growth & development; D011938:Rec A Recombinases / Q000235:genetics; D013014:SOS Response, Genetics / Q000187:drug effects*; D012697:Serine Endopeptidases / Q000235:genetics; D013312:Stress, Physiological / Q000187:drug effects / Q000235:genetics; D000099160:LexA Repressor Protein
chemical_list: D001426:Bacterial Proteins; D006918:Hydroxyurea; D019384:Nucleic Acid Synthesis Inhibitors; D011938:Rec A Recombinases; D012697:Serine Endopeptidases; D000099160:LexA Repressor Protein