Molecular analysis of cytolysin A (ClyA) in pathogenic Escherichia coli strains.
Cytolysin A (ClyA) of Escherichia coli is a pore-forming hemolytic protein encoded by the clyA (hlyE, sheA) gene that was first identified in E. coli K-12. In this study we examined various clinical E. coli isolates with regard to the presence and integrity of clyA. PCR and DNA sequence analyses demonstrated that 19 of 23 tested Shiga toxin-producing E. coli (STEC) strains, all 7 tested enteroinvasive E. coli (EIEC) strains, 6 of 8 enteroaggregative E. coli (EAEC) strains, and 4 of 7 tested enterotoxigenic E. coli (ETEC) strains possess a complete clyA gene. The remaining STEC, EAEC, and ETEC strains and 9 of the 17 tested enteropathogenic E. coli (EPEC) strains were shown to harbor mutant clyA derivatives containing 1-bp frameshift mutations that cause premature termination of the coding sequence. The other eight EPEC strains and all tested uropathogenic and new-born meningitis-associated E. coli strains (n = 14 and 3, respectively) carried only nonfunctional clyA fragments due to the deletion of two sequences of 493 bp and 204 or 217 bp at the clyA locus. Expression of clyA from clinical E. coli isolates proved to be positively controlled by the transcriptional regulator SlyA. Several tested E. coli strains harboring a functional clyA gene produced basal amounts of ClyA when grown under standard laboratory conditions, but most of them showed a clyA-dependent hemolytic phenotype only when SlyA was overexpressed. The presented data indicate that cytolysin A can play a role only for some of the pathogenic E. coli strains.
Institut für Medizinische Mikrobiologie, Klinikum der Johann Wolfgang Goethe-Universität, 60596 Frankfurt am Main, Germany. albrecht.ludwig@em.uni-frankfurt.de
Albrecht
A
Ludwig
Christine
C
von Rhein
Susanne
S
Bauer
Christian
C
Hüttinger
Werner
W
Goebel
D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000235:genetics / Q000502:physiology / Q000633:toxicity; D018389:Codon, Nonsense; D004269:DNA, Bacterial / Q000032:analysis / Q000737:chemistry / Q000302:isolation & purification; D004926:Escherichia coli / Q000235:genetics* / Q000302:isolation & purification / Q000472:pathogenicity; D004927:Escherichia coli Infections / Q000382:microbiology; D029968:Escherichia coli Proteins / Q000737:chemistry / Q000235:genetics* / Q000633:toxicity*; D016368:Frameshift Mutation; D015964:Gene Expression Regulation, Bacterial; D005798:Genes, Bacterial; D006460:Hemolysin Proteins / Q000737:chemistry / Q000235:genetics* / Q000633:toxicity*; D006461:Hemolysis; D008969:Molecular Sequence Data; D016133:Polymerase Chain Reaction; D016415:Sequence Alignment; D017422:Sequence Analysis, DNA; D017384:Sequence Deletion; D014157:Transcription Factors / Q000502:physiology; D037521:Virulence Factors / Q000235:genetics / Q000633:toxicity
D001426:Bacterial Proteins; D018389:Codon, Nonsense; D004269:DNA, Bacterial; D029968:Escherichia coli Proteins; D006460:Hemolysin Proteins; D014157:Transcription Factors; D037521:Virulence Factors; C119944:hlyE protein, E coli; C056785:salmolysin