title: The localized adherence pattern of an atypical enteropathogenic Escherichia coli is mediated by intimin omicron and unexpectedly promotes HeLa cell invasion.
abstract: Enteropathogenic Escherichia coli (EPEC) forms attaching and effacing lesions in the intestinal mucosa characterized by intimate attachment to the epithelium by means of intimin (an outer membrane adhesin encoded by eae). EPEC is subgrouped into typical (tEPEC) and atypical (aEPEC); only tEPEC carries the EAF (EPEC adherence factor) plasmid that encodes the bundle-forming pilus (BFP). Characteristically, after 3 h of incubation, tEPEC produces localized adherence (LA) (with compact microcolonies) in HeLa/HEp-2 cells by means of BFP, whereas most aEPEC form looser microcolonies. We have previously identified nine aEPEC strains displaying LA in extended (6 h) assays (LA6). In this study, we analysed the kinetics of LA6 pattern development and the role of intimin in the process. Transmission electron microscopy and confocal laser microscopy showed that the invasive process of strain 1551-2 displays a LA phenotype. An eae-defective mutant of strain 1551-2 prevented the invasion although preserving intense diffused adherence. Sequencing of eae revealed that strain 1551-2 expresses the omicron subtype of intimin. We propose that the LA phenotype of aEPEC strain 1551-2 is mediated by intimin omicron and hypothesize that this strain expresses an additional novel adhesive structure. The present study is the first to report the association of compact microcolony formation and an intense invasive ability in aEPEC.
authors.affiliation: Departamento de Microbiologia, Imunologia e Parasitologia da Universidade Federal de São Paulo, Escola Paulista de Medicina, São Paulo, Brazil.
authors.forename: Rodrigo Tavanelli
authors.initials: RT
authors.lastname: Hernandes
authors.forename: Rosa Maria
authors.initials: RM
authors.lastname: Silva
authors.forename: Sylvia Mendes
authors.initials: SM
authors.lastname: Carneiro
authors.forename: Fábia Andréia
authors.initials: FA
authors.lastname: Salvador
authors.forename: Maria Cecília Di Ciero
authors.initials: MC
authors.lastname: Fernandes
authors.forename: Ana Carolina Barbosa
authors.initials: AC
authors.lastname: Padovan
authors.forename: Denise
authors.initials: D
authors.lastname: Yamamoto
authors.forename: Renato Arruda
authors.initials: RA
authors.lastname: Mortara
authors.forename: Waldir Pereira
authors.initials: WP
authors.lastname: Elias
authors.forename: Marcelo Ribeiro
authors.initials: MR
authors.lastname: da Silva Briones
authors.forename: Tânia Aparecida Tardelli
authors.initials: TA
authors.lastname: Gomes
mesh_terms: D000199:Actins / Q000378:metabolism; D018829:Adhesins, Bacterial / Q000737:chemistry / Q000502:physiology*; D000595:Amino Acid Sequence; D001422:Bacterial Adhesion / Q000502:physiology*; D054308:Enteropathogenic Escherichia coli / Q000235:genetics / Q000472:pathogenicity* / Q000648:ultrastructure; D029968:Escherichia coli Proteins / Q000737:chemistry / Q000378:metabolism / Q000502:physiology*; D006367:HeLa Cells; D006801:Humans; D046529:Microscopy, Electron, Transmission; D008969:Molecular Sequence Data; D010641:Phenotype; D010766:Phosphorylation; D011956:Receptors, Cell Surface / Q000378:metabolism; D016415:Sequence Alignment
chemical_list: D000199:Actins; D018829:Adhesins, Bacterial; D029968:Escherichia coli Proteins; D011956:Receptors, Cell Surface; C109287:Tir protein, E coli; C073819:eaeA protein, E coli