Functional analysis of the minor subunits of S fimbrial adhesin (SfaI) in pathogenic Escherichia coli

ABSTRACT Among the virulence factors present in pathogenic extraintestinal Escherichia coli strains, expression of fimbrial adhesins is necessary for attachment to the host tissues and subsequent colonization. Occurrence of the sfa determinant coding for the S fimbriae is widespread among the uropathogens and meningitis isolates. The sfa operon consists of nine genes. In the biogenesis of S fimbriae, the proteins encoded by the sfa genes are presumably required in a specific stoichiometry. In the present work we studied how differential expression of the sfa operon genes occurs. Our findings indicate that a number of endoribonucleolytic cleavages occur in the mRNA from the sfa operon, and we detected the presence of different distinct transcriptional products, including sfaBA, sfaA, sfaADE, and sfaGSH. The sfaGSH transcript represents the three distal genes of the sfa operon, which code for the minor subunits of the S fimbriae. Analysis of the proteins in S fimbriae suggested that expression of the sfaGSH transcript provides equimolar amounts of the minor subunits. Furthermore, we showed that in the generation of the major sfaA transcript, the processing included RNase E endoribonuceolytic cleavage of the precursor sfaBA transcript. We suggest that posttranscriptional mRNA processing events result in differential gene expression important to achieve the stoichiometry necessary for fimbrial adhesin biogenesis.

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Canine Feces as a Reservoir of Extraintestinal Pathogenic Escherichia coli

Infection and Immunity ◽

10.1128/iai.69.3.1306-1314.2001 ◽

2001 ◽

Vol 69 (3) ◽

pp. 1306-1314 ◽

Cited By ~ 55

Author(s):

James R. Johnson ◽

Adam L. Stell ◽

Parissa Delavari

Keyword(s):

Escherichia Coli ◽

Dna Analysis ◽

Random Amplified Polymorphic Dna ◽

Clinical Isolates ◽

Fecal Samples ◽

E Coli ◽

Pathogenic Escherichia Coli ◽

Structural Subunit ◽

Fimbrial Adhesin ◽

Novel Allele

ABSTRACT To test the canine reservoir hypothesis of extraintestinal pathogenic Escherichia coli (ExPEC), 63 environmental canine fecal deposits were evaluated for the presence of ExPEC by a combination of selective culturing, extended virulence genotyping, hemagglutination testing, O serotyping, and PCR-based phylotyping. Overall, 30% of canine fecal samples (56% of those that yielded viable E. coli) contained papG-positiveE. coli, usually as the predominant E. colistrain and always possessing papG allele III (which encodes variant III of the P-fimbrial adhesin molecule PapG). Multiple other virulence-associated genes typical of human ExPEC were prevalent among the canine fecal isolates. According to serotyping, virulence genotyping, and random amplified polymorphic DNA analysis, over 50% ofpapG-positive fecal E. coli could be directly correlated with specific human clinical isolates from patients with cystitis, pyelonephritis, bacteremia, or meningitis, including archetypal human ExPEC strains 536, CP9, and RS218. Five canine fecal isolates and (clonally related) archetypal human pyelonephritis isolate 536 were found to share a novel allele of papA (which encodes the P-fimbrial structural subunit PapA). These data confirm that ExPEC representing known virulent clones are highly prevalent in canine feces, which consequently may provide a reservoir of ExPEC for acquisition by humans.

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High-Resolution Two-Locus Clonal Typing of Extraintestinal Pathogenic Escherichia coli

Applied and Environmental Microbiology ◽

10.1128/aem.06663-11 ◽

2012 ◽

Vol 78 (5) ◽

pp. 1353-1360 ◽

Cited By ~ 129

Author(s):

Scott J. Weissman ◽

James R. Johnson ◽

Veronika Tchesnokova ◽

Mariya Billig ◽

Daniel Dykhuizen ◽

...

Keyword(s):

Escherichia Coli ◽

Bacterial Species ◽

Discrimination Power ◽

Content Type ◽

E Coli ◽

Pathogenic Escherichia Coli ◽

Sequence Types ◽

Fimbrial Adhesin ◽

Internal Fragment

ABSTRACTMultilocus sequence typing (MLST) is usually based on the sequencing of 5 to 8 housekeeping loci in the bacterial chromosome and has provided detailed descriptions of the population structure of bacterial species important to human health. However, even strains with identical MLST profiles (known as sequence types or STs) may possess distinct genotypes, which enable different eco- or pathotypic lifestyles. Here we describe a two-locus, sequence-based typing scheme forEscherichia colithat utilizes a 489-nucleotide (nt) internal fragment offimH(encoding the type 1 fimbrial adhesin) and the 469-nt internalfumCfragment used in standard MLST. Based on sequence typing of 191 model commensal and pathogenic isolates plus 853 freshly isolated clinicalE. colistrains, this 2-locus approach—which we call CH (fumC/fimH) typing—consistently yielded more haplotypes than standard 7-locus MLST, splitting large STs into multiple clonal subgroups and often distinguishing different within-ST eco- and pathotypes. Furthermore, specific CH profiles corresponded to specific STs, or ST complexes, with 95% accuracy, allowing excellent prediction of MLST-based profiles. Thus, 2-locus CH typing provides a genotyping tool for molecular epidemiology analysis that is more economical than standard 7-locus MLST but has superior clonal discrimination power and, at the same time, corresponds closely to MLST-based clonal groupings.

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