title: Molecular characterization and distribution of genes encoding members of the type III effector nleA family among pathogenic Escherichia coli strains.
abstract: In this study, we investigated the occurrence of the previously described gene nleA(4795) and variants of nleA, putatively encoding non-locus-of-enterocyte-effacement-encoded type III effector proteins with functions that are unknown. nleA variants were detected in 150 out of 170 enteropathogenic Escherichia coli strains and enterohemorrhagic E. coli strains, two of them being eae negative. Besides the known variants nleA(4795), Z6024, and the espI-like gene, 11 novel nleA variants with different lengths and sequence identities at the deduced amino acid level (between 71% and 96%) have been identified. Whereas most of the serogroups associated with more severe disease were quite homogenous with respect to the presence of a particular nleA variant, other serogroups were not. Moreover, Southern blot hybridization revealed that certain strains carry two copies of nleA in their chromosome, frequently encoding different variants. In most cases, the open reading frame of one of the copies was disrupted, usually by an insertion element. Furthermore, transmission of the type III effector-encoding gene could be shown by transduction of nleA-carrying bacteriophages to a laboratory E. coli strain.
authors.affiliation: Institute of Food Science and Biotechnology, Department of Food Microbiology, University of Hohenheim, 70599 Stuttgart, Germany.
authors.forename: Kristina
authors.initials: K
authors.lastname: Creuzburg
authors.forename: Herbert
authors.initials: H
authors.lastname: Schmidt
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D015139:Blotting, Southern; D002876:Chromosomes, Bacterial / Q000235:genetics; D004251:DNA Transposable Elements / Q000235:genetics; D004269:DNA, Bacterial / Q000737:chemistry / Q000235:genetics; D004926:Escherichia coli / Q000235:genetics* / Q000302:isolation & purification; D004927:Escherichia coli Infections / Q000382:microbiology* / Q000662:veterinary*; D029968:Escherichia coli Proteins / Q000235:genetics*; D018628:Gene Dosage; D006801:Humans; D008969:Molecular Sequence Data; D016415:Sequence Alignment; D017422:Sequence Analysis, DNA; D017386:Sequence Homology, Amino Acid; D014161:Transduction, Genetic; D037521:Virulence Factors / Q000235:genetics*
chemical_list: D004251:DNA Transposable Elements; D004269:DNA, Bacterial; D029968:Escherichia coli Proteins; C488216:NleA protein, E coli; D037521:Virulence Factors