PDBsum entry 1iec

Hydrolase

PDB id: 1iec

Contents

Protein chains

207 a.a. *

219 a.a. *

Waters ×144

* Residue conservation analysis

PDB id:

1iec

Name:

Hydrolase

Title:

Crystal structure of the catalytic site mutant (h157a) of the human cytomegalovirus protease

Structure:

Capsid protein p40: assemblin protease. Chain: a, b. Fragment: residues 1-256. Synonym: hcmv protease. Engineered: yes. Mutation: yes

Source:

Human herpesvirus 5. Organism_taxid: 10360. Strain: ad169. Gene: ul80. Expressed in: escherichia coli. Expression_system_taxid: 562

Biol. unit:

Dimer (from PQS)

Resolution:

2.20Å R-factor: 0.226 R-free: 0.269

Authors:

R.Khayat,R.Batra,M.J.Massariol,L.Lagace,L.Tong

Key ref:

R.Khayat et al. (2001). Investigating the role of histidine 157 in the catalytic activity of human cytomegalovirus protease. Biochemistry, 40, 6344-6351. PubMed id: 11371196 DOI: 10.1021/bi010158b

Date:

09-Apr-01 Release date: 06-Jun-01

Protein chain

P16753  (SCAF_HCMVA) -  Capsid scaffolding protein from Human cytomegalovirus (strain AD169)

Seq: 708 a.a.

Struc: 207 a.a.*

Protein chain

P16753  (SCAF_HCMVA) -  Capsid scaffolding protein from Human cytomegalovirus (strain AD169)

Seq: 708 a.a.

Struc: 219 a.a.*

* PDB and UniProt seqs differ at 4 residue positions (black crosses)

Enzyme reactions

• Enzyme class: Chains A, B: E.C.3.4.21.97 - assemblin.
• Reaction: Cleaves -Ala-|-Ser- and -Ala-|-Ala- bonds in the scaffold protein.

DOI no: 10.1021/bi010158b

Biochemistry 40:6344-6351 (2001)

PubMed id: 11371196

Investigating the role of histidine 157 in the catalytic activity of human cytomegalovirus protease.

R.Khayat, R.Batra, M.J.Massariol, L.Lagacé, L.Tong.

ABSTRACT

Herpesvirus 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.