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Please use this identifier to cite or link to this item: http://hdl.handle.net/1807/18767

Title: Autocatalytic Activation and Characterization of Staphylococcus aureus Cysteine Protease Staphopain A
Authors: Ip, Jessica
Advisor: McGavin, Martin
Department: Laboratory Medicine and Pathobiology
Keywords: Protease
Staphylococcus
Virulence
Issue Date: 12-Feb-2010
Abstract: Staphylococcus aureus secretes two cysteine proteases, Staphopain A (scpA) and Staphopain B (sspB). We hypothesized that ScpA will exhibit a distinct activation mechanism, and a different or complementary substrate specificity compared to SspB. A Cys>Ala active site substitution led to the accumulation of unprocessed 40-kDa proScpA, confirming that ScpA undergoes autocatalytic activation. A temporal analysis of ScpA expression revealed that activation was initiated by processing at Lys171 and Glu176, producing an intermediate that was rapidly converted to several isoforms of mature protease by processing after Thr202, Lys209, Thr214 and Asn216. Consistent with broad specificity, mature ScpA was sensitive to autocatalytic degradation. ScpA demonstrated activity towards elastin, fibrinogen and indicated evidence for binding to heparin. Elastinolytic activity was uniquely associated with strains belonging to CC30, and was correlated with ScpA expression. Therefore, although ScpA and SspB share both sequence and structural similarity, they exhibited very different substrate specificities and activation mechanisms.
URI: http://hdl.handle.net/1807/18767
Appears in Collections:Master
Department of Laboratory Medicine and Pathobiology - Master theses

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