Abstract
Serine protease autotransporters of Enterobacteriaceae (SPATEs) are secreted proteins that contribute to virulence and function as proteases, toxins, adhesins, and/or immunomodulators. An extra-intestinal pathogenic E. coli (ExPEC) O1:K1 strain, QT598, isolated from a turkey, was shown to contain vat, tsh, and three uncharacterized SPATE-encoding genes. Uncharacterized SPATEs: Sha (Serine-protease hemagglutinin autotransporter), TagB and TagC (tandem autotransporter genes B and C) were tested for activities including hemagglutination, autoaggregation, and cytotoxicity when expressed in E. coli K-12. Sha and TagB conferred autoaggregation and hemagglutination activities. TagB, TagC, and Sha all exhibited cytopathic effects on a bladder epithelial cell line. In QT598, tagB and tagC are tandemly encoded on a genomic island, and were present in 10% of UTI isolates and 4.7% of avian E. coli. Sha is encoded on a virulence plasmid and was present in 1% of UTI isolates and 20% of avian E. coli. To specifically examine the role of SPATEs for infection, the 5 SPATE genes were deleted from strain QT598 and tested for cytotoxicity. Loss of all five SPATEs abrogated the cytopathic effect on bladder epithelial cells, although derivatives producing any of the 5 SPATEs retained cytopathic activity. In mouse infections, sha gene-expression was up-regulated a mean of sixfold in the bladder compared to growth in vitro. Loss of either tagBC or sha did not reduce urinary tract colonization. Deletion of all 5 SPATEs, however, significantly reduced competitive colonization of the kidney supporting a cumulative role of SPATEs for QT598 in the mouse UTI model.
Keywords:
Autotransporters; SPATE; Toxins; avian pathogenic; mouse infection; poultry; serine protease autotransporter; uropathogenic.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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Animals
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Bacterial Toxins / metabolism
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Cell Line
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Escherichia coli Infections / microbiology
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Extraintestinal Pathogenic Escherichia coli / genetics*
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Extraintestinal Pathogenic Escherichia coli / pathogenicity
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Female
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Genome, Bacterial
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Humans
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Kidney / microbiology*
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Mice
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Phylogeny
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Serine Proteases / genetics
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Serine Proteases / metabolism*
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Type V Secretion Systems / genetics
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Type V Secretion Systems / metabolism*
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Urinary Tract / microbiology
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Virulence
Substances
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Bacterial Toxins
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Type V Secretion Systems
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Serine Proteases
Grants and funding
This work was supported by the Institut Pasteur [ACIP]; Natural Sciences and Engineering Research Council of Canada [2014-06622] and [2019-06642].