Crystal structure of calpain reveals the structural basis for Ca(2+)-dependent protease activity and a novel mode of enzyme activation.Hosfield, C.M., Elce, J.S., Davies, P.L., Jia, Z.
(1999) EMBO J. 18: 6880-6889
- PubMed: 10601010
- DOI: 10.1093/emboj/18.24.6880
- Also Cited By: 3DF0
- PubMed Abstract:
- Crystal Structure of Calcium Bound Domain VI of Calpain at 1.9 A Resolution and its Role in Enzyme Assembly, Regulation, and Inhibitor Binding
Lin, G.D.,Chattopadhyay, D.,Maki, M.,Wang, K.K.,Carson, M.,Jin, L.,Hatanaka, M.,Takano, E.,Narayana, S.V.
(1997) Nat.Struct.Mol.Biol. 4: 539
- Structure of a Calpain Ca(2+)-Binding Domain Reveals a Novel EF-Hand and Ca(2+) -Induced Conformational Changes
Blanchard, H.,Grochulski, P.,Li, Y.,Arthur, J.S.C.,Davies, P.L.,Elce, J.S.,Cygler, M.
(1997) Nat.Struct.Mol.Biol. 4: 532
- Crystallization and X-Ray Crystallographic Analysis of M-Calpain: A Ca2+- Dependent Protease
Hosfield, C.M.,Ye, Q.,Arthur, J.S.C.,Hegadorn, C.,Croall, D.E.,Elce, J.S.,Jia, Z.
(1999) Acta Crystallogr.,Sect.D 55: 1484
The combination of thiol protease activity and calmodulin-like EF-hands is a feature unique to the calpains. The regulatory mechanisms governing calpain activity are complex, and the nature of the Ca(2+)-induced switch between inactive and active for ...
The combination of thiol protease activity and calmodulin-like EF-hands is a feature unique to the calpains. The regulatory mechanisms governing calpain activity are complex, and the nature of the Ca(2+)-induced switch between inactive and active forms has remained elusive in the absence of structural information. We describe here the 2.6 A crystal structure of m-calpain in the Ca(2+)-free form, which illustrates the structural basis for the inactivity of calpain in the absence of Ca(2+). It also reveals an unusual thiol protease fold, which is associated with Ca(2+)-binding domains through heterodimerization and a C(2)-like beta-sandwich domain. Strikingly, the structure shows that the catalytic triad is not assembled, indicating that Ca(2+)-binding must induce conformational changes that re-orient the protease domains to form a functional active site. The alpha-helical N-terminal anchor of the catalytic subunit does not occupy the active site but inhibits its assembly and regulates Ca(2+)-sensitivity through association with the regulatory subunit. This Ca(2+)-dependent activation mechanism is clearly distinct from those of classical proteases.
Department of Biochemistry, Queen's University and The Protein Engineering Network of Centres of Excellence, Kingston, Ontario, Canada K7L 3N6.