2H6M

An episulfide cation (thiiranium ring) trapped in the active site of HAV 3C proteinase inactivated by peptide-based ketone inhibitors

Summary for 2H6M

• Entry DOI: 10.2210/pdb2h6m/pdb
• Related: 1HAV 1QA7 2A4O 2CXV
• Related PRD ID: PRD_000423
• Descriptor: Picornain 3C, N-ACETYL-LEUCYL-ALANYL-ALANYL-(N,N-DIMETHYL)-GLUTAMINE-(1,4-DIOXO-3,4-DIHYDRO-1H-PHTHALAZIN-2-YL)METHYLKETONE INHIBITOR, N-[(BENZYLOXY)CARBONYL]-L-ALANINE, ... (4 entities in total)
• Functional Keywords: beta barrel, hydrolase-hydrolase inhibitor complex, hydrolase/hydrolase inhibitor
• Biological source: Hepatitis A virus
• Cellular location: Protein VP2: Virion (By similarity). Protein VP3: Virion (By similarity). Protein VP1: Virion (By similarity). Protein VP1-2A: Virion (By similarity). Protein 2B: Host cytoplasmic vesicle membrane; Peripheral membrane protein; Cytoplasmic side (Potential). Protein 2C: Host cytoplasmic vesicle membrane; Peripheral membrane protein; Cytoplasmic side (Potential). Protein 3ABC: Host cytoplasmic vesicle membrane; Peripheral membrane protein; Cytoplasmic side (Potential). Protein 3AB: Host cytoplasmic vesicle membrane; Peripheral membrane protein; Cytoplasmic side (Potential). Protein 3A: Host cytoplasmic vesicle membrane; Peripheral membrane protein; Cytoplasmic side (Potential). Protein 3B: Virion (Potential). Picornain 3C: Host cytoplasm (Potential). RNA-directed RNA polymerase 3D-POL: Host cytoplasmic vesicle membrane; Peripheral membrane protein; Cytoplasmic side (Potential): P06441
• Total number of polymer chains: 2
• Total formula weight: 23983.64

Authors

Yin, J.,Cherney, M.M.,Bergmann, E.M.,James, M.N. (deposition date: 2006-05-31, release date: 2006-08-08, Last modification date: 2021-10-20)

Primary citation

Yin, J.,Cherney, M.M.,Bergmann, E.M.,Zhang, J.,Huitema, C.,Pettersson, H.,Eltis, L.D.,Vederas, J.C.,James, M.N.
An episulfide cation (thiiranium ring) trapped in the active site of HAV 3C proteinase inactivated by peptide-based ketone inhibitors.
J.Mol.Biol., 361:673-686, 2006

PubMed Abstract: We have solved the crystal and molecular structures of hepatitis A viral (HAV) 3C proteinase, a cysteine peptidase having a chymotrypsin-like protein fold, in complex with each of three tetrapeptidyl-based methyl ketone inhibitors to resolutions beyond 1.4 A, the highest resolution to date for a 3C or a 3C-Like (e.g. SARS viral main proteinase) peptidase. The residues of the beta-hairpin motif (residues 138-158), an extension of two beta-strands of the C-terminal beta-barrel of HAV 3C are critical for the interactions between the enzyme and the tetrapeptide portion of these inhibitors that are analogous to the residues at the P4 to P1 positions in the natural substrates of picornaviral 3C proteinases. Unexpectedly, the Sgamma of Cys172 forms two covalent bonds with each inhibitor, yielding an unusual episulfide cation (thiiranium ring) stabilized by a nearby oxyanion. This result suggests a mechanism of inactivation of 3C peptidases by methyl ketone inhibitors that is distinct from that occurring in the structurally related serine proteinases or in the papain-like cysteine peptidases. It also provides insight into the mechanisms underlying both the inactivation of HAV 3C by these inhibitors and on the proteolysis of natural substrates by this viral cysteine peptidase.

PubMed: 16860823
DOI: 10.1016/j.jmb.2006.06.047

Experimental method

X-RAY DIFFRACTION (1.4 Å)