Proteomic and microarray characterization of the AggR regulon identifies a pheU pathogenicity island in enteroaggregative Escherichia coli.
Mol Microbiol
; 61(5): 1267-82, 2006 Sep.
Article
em En
| MEDLINE
| ID: mdl-16925558
ABSTRACT
Enteroaggregative Escherichia coli (EAEC) is defined by aggregative adherence (AA) to HEp-2 cells, where bacteria display adherence to cell surfaces and also to the intervening substratum in a stacked-brick configuration. We previously showed that an AraC homologue designated AggR is required for the expression of plasmid-encoded genes that mediate AA of EAEC strain 042. In this study, we hypothesized that AggR also controls the expression of other virulence determinants in EAEC 042. Using proteomic and microarray analysis, we identified for the first time that AggR activates the expression of chromosomal genes, including 25 contiguous genes (aaiA-Y), which are localized to a 117 kb pathogenicity island (PAI) inserted at pheU. Many of these genes have homologues in other Gram-negative bacteria and were recently proposed to constitute a type VI secretion system (T6SS). AaiC was identified as a secreted protein that has no apparent homologues within GenBank. EAEC strains carrying in-frame deletions of aaiB, aaiG, aaiO or aaiP still synthesized AaiC; however, AaiC secretion was abolished. Cloning of aai genes into E. coli HB101 suggested that aaiA-P are sufficient for AaiC secretion. A second T6SS was identified within the pheU PAI that secretes a protein unrelated by sequence identity to AaiC. Distribution studies indicated that aaiA and aaiC are commonly found in EAEC isolates worldwide, particularly in strains defined as typical EAEC. These data support the hypothesis that AggR is a global regulator of EAEC virulence determinants, and builds on the hypothesis that T6SS is an importance mediator of pathogenesis.
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Base de dados:
MEDLINE
Assunto principal:
Transativadores
/
Análise de Sequência com Séries de Oligonucleotídeos
/
Proteínas de Escherichia coli
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Proteômica
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Ilhas Genômicas
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Escherichia coli
Tipo de estudo:
Prognostic_studies
Idioma:
En
Ano de publicação:
2006
Tipo de documento:
Article