Structure of granzyme C reveals an unusual mechanism of protease autoinhibition

Dion Kaiserman, Ashley Maurice Buckle, Petra Van Damme, James Alexander Irving, Ruby Hong Ping Law, Antony Yaron Matthews, Tanya Ann Bashtannyk-Puhalovich, Christopher Langendorf, Philip Thompson, Joel Vandekerckhove, Kris Gevaert, James C Whisstock, Phillip Ian Bird

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25 Citations (Scopus)


Proteases act in important homeostatic pathways and are tightly regulated. Here, we report an unusual structural mechanism of regulation observed by the 2.5-A X-ray crystal structure of the serine protease, granzyme C. Although the active-site triad residues adopt canonical conformations, the oxyanion hole is improperly formed, and access to the primary specificity (S1) pocket is blocked through a reversible rearrangement involving Phe-191. Specifically, a register shift in the 190-strand preceding the active-site serine leads to Phe-191 filling the S1 pocket. Mutation of a unique Glu-Glu motif at positions 192-193 unlocks the enzyme, which displays chymase activity, and proteomic analysis confirms that activity of the wild-type protease can be released through interactions with an appropriate substrate. The 2.5-A structure of the unlocked enzyme reveals unprecedented flexibility in the 190-strand preceding the active-site serine that results in Phe-191 vacating the S1 pocket. Overall, these observations describe a broadly applicable mechanism of protease regulation that cannot be predicted by template-based modeling or bioinformatic approaches alone.
Original languageEnglish
Pages (from-to)5587 - 5592
Number of pages6
JournalProceedings of the National Academy of Sciences of the United States of America
Issue number14
Publication statusPublished - 2009

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