Enteroaggregative Escherichia coli (EAEC) is an increasingly important cause of diarrhea in both developing and industrialized countries, and is characterized by strong biofilm formation on the intestinal mucosa. Sequencing of the virulent plasmid pAA2 of the prototype EAEC 042 revealed a cluster of three open reading frames (ORFs; shf, capU, and virK) ca. 93% identical to a similar cluster located in Shigella flexneri. The function of the first ORF Shf protein is not known, but the closest well-characterized homologue is the IcaB protein of Staphylococcus epidermidis, which plays a crucial role in exopolysaccharide modification in bacterial biofilm formation. To investigate the role of this cluster in the virulence of EAEC, we mutated three genes at this locus. All the mutants maintained the aggregative phenotype in the liquid phase. However, the insertional mutant of shf formed a less abundant biofilm in a microtiter plate assay than did the wild type, while the capU mutant and the virK mutant did not. The complementation of the shf mutant with this cluster restored the thick biofilm similar to that of the wild type. The shf transcriptional level decreased in the transcriptional regulator aggR mutant and was restored when the mutant was complemented with aggR. These results suggest that the shf gene is required for the firm biofilm formation of EAEC 042, and transcription of the shf gene is dependent on AggR.
The shf Gene of a Shigella flexneri Homologue on the Virulent Plasmid pAA2 of Enteroaggregative Escherichia coli 042 Is Required for Firm Biofilm Formation
엔테로응집성 대장균 042의 병원성 플라스미드 pAA2에 있는 시겔라 플렉스네리 동종 유전자의 shf는 강한 바이오필름 형성에 필요하다.
[Category] 세균성이질,
[Article Type] journal-article
[Source] pubmed
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