Characterization of the StcE protease activity of Escherichia coli O157:H7

Thomas Grys, Laura L. Walters, Rodney A. Welch

Research output: Contribution to journalArticle

23 Citations (Scopus)

Abstract

The StcE zinc metalloprotease is secreted by enterohemorrhagic Escherichia coli (EHEC) O157:H7 and contributes to intimate adherence of this bacterium to host cells, a process essential for mammalian colonization. StcE has also been shown to localize the inflammatory regulator C1 esterase inhibitor (C1-INH) to cell membranes. We tried to more fully characterize StcE activity to better understand its role in EHEC pathogenesis. StcE was active at pH 6.1 to 9.0, in the presence of NaCI concentrations ranging from 0 to 600 mM, and at 4°C to 55°C. Interestingly, antisera against StcE or C1-INH did not eliminate StcE cleavage of C1-INH. Treatment of StcE with the proteases trypsin, chymotrypsin, human nentrophil elastase, and Pseudomonas aeruginosa elastase did not eliminate StcE activity against C1-INH. After StcE was kept at 23°C for 65 days, it exhibited full proteolytic activity, and it retained 30% of its original activity after incubation for 8 days at 37°C. Together, these results show the StcE protease is a stable enzyme that is probably active in the environment of the colon. Additionally, kcat/Km data showed that StcE proteolytic activity was 2.5-fold more efficient with the secreted mucin MUC7 than with the complement regulator C1-INH. This evidence supports a model which includes two roles for StcE during infection, in which StcE acts first as a mucinase and then as an anti-inflammatory agent by localizing C1-INH to cell membranes.

Original languageEnglish (US)
Pages (from-to)4646-4653
Number of pages8
JournalJournal of Bacteriology
Volume188
Issue number13
DOIs
StatePublished - Jul 1 2006
Externally publishedYes

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Complement C1 Inhibitor Protein
Escherichia coli O157
Peptide Hydrolases
Enterohemorrhagic Escherichia coli
hyaluronate lyase
Cell Membrane
Complement C1
Pancreatic Elastase
Metalloproteases
Mucins
Zinc
Immune Sera
Colon
Anti-Inflammatory Agents
Bacteria
Enzymes
Infection

ASJC Scopus subject areas

  • Microbiology
  • Molecular Biology

Cite this

Characterization of the StcE protease activity of Escherichia coli O157:H7. / Grys, Thomas; Walters, Laura L.; Welch, Rodney A.

In: Journal of Bacteriology, Vol. 188, No. 13, 01.07.2006, p. 4646-4653.

Research output: Contribution to journalArticle

Grys, Thomas ; Walters, Laura L. ; Welch, Rodney A. / Characterization of the StcE protease activity of Escherichia coli O157:H7. In: Journal of Bacteriology. 2006 ; Vol. 188, No. 13. pp. 4646-4653.
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