tailieunhanh - Báo cáo khoa học: Crystal structure of a designed tetratricopeptide repeat module in complex with its peptide ligand

Tetratricopeptide repeats (TPRs) are protein domains that mediate key protein–protein interactions in cells. Several TPR domains bind the C-ter-mini of the chaperones heat shock protein (Hsp)90 and⁄or Hsp70, and exchange of such binding partners is key for the heat shock response. | Crystal structure of a designed tetratricopeptide repeat module in complex with its peptide ligand Aitziber L. Cortajarena1 Jimin Wang1 and Lynne Regan1 2 1 Department of Molecular Biophysics Biochemistry Yale University New Haven CT USA 2 Department of Chemistry Yale University New Haven CT USA Keywords crystal structure Hsp90 protein design repeat proteins tetratricopeptide repeat TPR Correspondence L. Regan Department of Molecular Biophysics Biochemistry Yale University New Haven CT 06520 USA Fax 1 203 432 5175 Tel 1 203 432 9843 E-mail Website http reganlab Received 26 October 2009 revised 25 November 2009 accepted 16 December 2009 Tetratricopeptide repeats TPRs are protein domains that mediate key protein-protein interactions in cells. Several TPR domains bind the C-ter-mini of the chaperones heat shock protein Hsp 90 and or Hsp70 and exchange of such binding partners is key for the heat shock response. We have previously described the design of a TPR protein that binds tightly and specifically to the C-terminus of Hsp90 and in doing so is able to inhibit chaperone function in vivo. Here we present the X-ray crystal structure of the designed TPR domain CTPR390 in complex with its peptide ligand - the C-terminal residues of Hsp90 peptide MEEVD . This structure reveals two interesting aspects of the TPR modules. First a new packing arrangement of 3-TPR modules is observed. The TPR units stack against each other in an unusual fashion to form infinite superhelices in the crystal. Second the structure provides insights into the molecular basis of TPR-ligand recognition. doi Introduction The basic tetratricopeptide TPR repeat comprises 34 amino acids that adopt a helix-turn-helix structure 1 2 . We refer to the two tandem helices as the A-helix and B-helix. In tandem arrays of TPR repeats the helices stack to form superhelical structures that display two surfaces a concave binding face and a convex .