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Zongchao Jia

 
  Protein structure-function studies by X-ray crystallography

 
  Contact Information:  
  Associate Professor of Biochemistry
Ph.D., University of Saskatchewan;
NSERC Post-Doctoral Fellow, University of Oxford;
Canada Research Chair (Structural Biology);
Chancellor's Research Award;
Premier's Research Excellence Award

Tel: (613) 533-6277
Fax: (613) 533-2497
email: jia@post.queensu.ca


 
  Protein crystallography is a powerful tool capable of revealing atomic details of protein. The technique has been widely used to determine 3-D structures of proteins, multi-domain large protein complexes, protein-DNA interactions etc. Protein crystallography has in the last decade advanced greatly and made a major contribution to the fundamental understanding of biological processes and provided insights into problems of molecular recognition and biological control of importance to medicine and the pharmaceutical industry. In our lab, we are currently focusing on three classes of proteins - antifreeze proteins (supported by CIHR, Ca2+-dependent thiol protease calpain (supported by PENCE) and phosphatase/kinase (supported by NSERC).

Antifreeze proteins are found in a variety of species such as fish, insects and plants. They have the unique capability to bind to ice seed crystals and prevent them from further growth, therefore avoiding and/or lessening the damage to the host. Our research focus is to determine the 3-D structures of these antifreeze proteins and reveal the structural basis for their ice-binding properties.

Calpains have the unique feature in coupling cysteine protease activity and calmodulin-like EF-hands. We have recently determined the first structure of calpain, which reveals an unusual thiol protease fold associated with Ca2+-binding domains. In the absence of Ca2+, the structure shows that the active site is not assembled, suggesting that Ca2+-induced conformational changes move the protease domains to form a functional enzyme.

Phosphatase/kinase are involved in a wide range of cellular processes. Escherichia coli phytase is a member of the histidine acid phosphatase family. Our recently determined structures of the phytase and its complex with phytic acid have revealed a unique mechanism of coupling substrate binding with catalysis.

Ribbon picture of E. coli phytase complexed with natural substrate phytate (Lim et al., Nature Structural Biology, 7:108-133 (2000))



 
  Publications:  
  C.M. Hosfield, T. Moldoveanu, P.L. Davies, J.S. Elce and Z. Jia. (2001) Calpain mutants with increased Ca2+-sensitivity and implications for the role of the C2-like domain III. J. Biol. Chem. 276, 7404-7407.

Y.-C. Liou, A. Tocilj, P.L. Davies and Z. Jia. (2000) Mimicry of ice structure by surface hydroxyls and water of a b-helix antifreeze protein. Nature, 406, 322-324.

D. Lim, S. Golovan, C.W. Forsberg and Z. Jia. (2000) Crystal structures of Escherichia coli phytase and its complex with phytate. Nature Structure Biology, 7, 108-113.

C.M. Hosfield, J.S. Elce, P.L. Davies and Z. Jia. (1999) Crystal structure of calpain reveals the structural basis for Ca2+-dependent protease activity and a novel mode of enzyme activation. EMBO Journal, 18, 6880-6889.