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Rapid autocatalytic activation of the M4 metalloprotease aureolysin is controlled by a conserved N‐terminal fungalysin‐thermolysin‐propeptide domain
Author(s) -
Nickerson Nicholas N.,
Joag Vineet,
McGavin Martin J.
Publication year - 2008
Publication title -
molecular microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.857
H-Index - 247
eISSN - 1365-2958
pISSN - 0950-382X
DOI - 10.1111/j.1365-2958.2008.06384.x
Subject(s) - protein precursor , metalloproteinase , thermolysin , zymogen , biology , protease , adamts , microbiology and biotechnology , biochemistry , matrix metalloproteinase , thrombospondin , enzyme , trypsin
Summary The Staphylococcus aureus proteolytic cascade consists of a metalloprotease aureolysin (Aur), which activates a serine protease zymogen proSspA, which in turn activates the SspB cysteine protease. As with other M4 metalloproteases, including elastase of Pseudomonas aeruginosa , the propeptide of proAur contains an N‐terminal fungalysin‐thermolysin‐propeptide (FTP) domain. Autocatalytic activation of proAur was initiated by processing at T85↓L 86 in the FTP domain. This differed from the mechanism described for proElastase, where the FTP domain has an RY motif in place of TL 86 , and processing occurred at the junction of the propeptide and metalloprotease domains, which remained as an inactive complex during passage across the outer membrane. When TL 86 in the FTP domain was replaced with RY, an intact N‐terminal propeptide was secreted, but the M4 metalloprotease domain was degraded. Consequently, this segment of the FTP domain promotes intramolecular processing of proAur while bestowing a chaperone function, but discourages processing within the FTP domain of proElastase, where activation must be co‐ordinated with passage across a second membrane. We conclude that the FTP domain of proAur is adapted to facilitate a rapid autocatalytic activation mechanism, consistent with the role or proAur as initiator of the staphylococcal proteolytic cascade.