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From Proteopedia
CRYSTAL STRUCTURE OF THE CATALYTIC SITE MUTANT (H157E) OF THE HUMAN CYTOMEGALOVIRUS PROTEASE
Structural highlights
Function[VP40_HCMVA] Capsid scaffolding protein acts as a scaffold protein by binding major capsid protein UL86 in the cytoplasm, inducing the nuclear localization of both proteins. Multimerizes in the nucleus such as protein UL86 forms the icosahedral T=16 capsid. Autocatalytic cleavage releases the assembly protein, and subsequently abolishes interaction with major capsid protein UL86. Cleavages products are evicted from the capsid before or during DNA packaging (By similarity). Assemblin is a protease essential for virion assembly in the nucleus. Catalyzes the cleavage of the assembly protein after complete capsid formation. Assemblin and cleavages products are evicted from the capsid before or during DNA packaging (By similarity). Assembly protein plays a major role in capsid assembly. Acts as a scaffold protein by binding major capsid protein UL86. Multimerizes in the nucleus such as protein UL86 forms the icosahedral T=16 capsid. Cleaved by assemblin after capsid completion. The cleavages products are evicted from the capsid before or during DNA packaging (By similarity). Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMedHerpesvirus proteases belong to a new class of serine proteases and contain a novel Ser-His-His catalytic triad, while classical serine proteases have an acidic residue as the third member. To gain a better understanding of the molecular basis for the functional role of the third-member His residue, we have carried out structural and biochemical investigations of human cytomegalovirus (HCMV) protease that bears mutations of the His157 third member. Kinetic studies showed that all the mutants have reduced catalytic activity. Structural studies revealed that a solvent molecule is hydrogen-bonded to the His63 second member and Ser134 in the H157A mutant, partly rescuing the activity of this mutant. This is confirmed by our kinetic and structural observations on the S134A/H157A double mutant, which showed further reductions in the catalytic activity. The structure of the H157A mutant is also in complex with the PMSF inhibitor. The H157E mutant has the best catalytic activity among the mutants; its structure, however, showed conformational readjustments of the His63 and Ser132 residues. The Ser132-His63 diad of HCMV protease has similar activity as the diads in classical serine proteases, whereas the contribution of the His157 third member to the catalysis is much smaller. Finally, structural comparisons revealed the presence of two conserved structural water molecules at the bottom of the S(1) pocket, suggesting a possible new direction for the design of HCMV protease inhibitors. Investigating the role of histidine 157 in the catalytic activity of human cytomegalovirus protease.,Khayat R, Batra R, Massariol MJ, Lagace L, Tong L Biochemistry. 2001 May 29;40(21):6344-51. PMID:11371196[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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