2OZK

Structure of an N-Terminal Truncated Form of Nendou (NSP15) From SARS-CORONAVIRUS

Summary for 2OZK

• Entry DOI: 10.2210/pdb2ozk/pdb
• Descriptor: Uridylate-specific endoribonuclease (1 entity in total)
• Functional Keywords: endonuclease nendou, ribonuclease, homolog of xenopus xendou, sars nsp15, n-terminal truncated construct, viral protein
• Biological source: SARS coronavirus
• Cellular location: Non-structural protein 3: Host membrane; Multi-pass membrane protein (Potential). Non-structural protein 4: Host membrane; Multi-pass membrane protein (Potential). Non-structural protein 6: Host membrane; Multi-pass membrane protein (Potential). Non-structural protein 7: Host cytoplasm, host perinuclear region (By similarity). Non-structural protein 8: Host cytoplasm, host perinuclear region (By similarity). Non-structural protein 9: Host cytoplasm, host perinuclear region (By similarity). Non-structural protein 10: Host cytoplasm, host perinuclear region (By similarity). Helicase: Host endoplasmic reticulum-Golgi intermediate compartment (Potential). Uridylate-specific endoribonuclease: Host cytoplasm, host perinuclear region (By similarity): P59641
• Total number of polymer chains: 4
• Total formula weight: 154131.19

Authors

Saikatendu, K.,Joseph, J.,Subramanian, V.,Neuman, B.,Buchmeier, M.,Stevens, R.C.,Kuhn, P. (deposition date: 2007-02-26, release date: 2007-05-29, Last modification date: 2024-11-06)

Primary citation

Joseph, J.S.,Saikatendu, K.S.,Subramanian, V.,Neuman, B.W.,Buchmeier, M.J.,Stevens, R.C.,Kuhn, P.
Crystal structure of a monomeric form of severe acute respiratory syndrome coronavirus endonuclease nsp15 suggests a role for hexamerization as an allosteric switch.
J.Virol., 81:6700-6708, 2007

PubMed Abstract: Mature nonstructural protein-15 (nsp15) from the severe acute respiratory syndrome coronavirus (SARS-CoV) contains a novel uridylate-specific Mn2+-dependent endoribonuclease (NendoU). Structure studies of the full-length form of the obligate hexameric enzyme from two CoVs, SARS-CoV and murine hepatitis virus, and its monomeric homologue, XendoU from Xenopus laevis, combined with mutagenesis studies have implicated several residues in enzymatic activity and the N-terminal domain as the major determinant of hexamerization. However, the tight link between hexamerization and enzyme activity in NendoUs has remained an enigma. Here, we report the structure of a trimmed, monomeric form of SARS-CoV nsp15 (residues 28 to 335) determined to a resolution of 2.9 A. The catalytic loop (residues 234 to 249) with its two reactive histidines (His 234 and His 249) is dramatically flipped by approximately 120 degrees into the active site cleft. Furthermore, the catalytic nucleophile Lys 289 points in a diametrically opposite direction, a consequence of an outward displacement of the supporting loop (residues 276 to 295). In the full-length hexameric forms, these two loops are packed against each other and are stabilized by intimate intersubunit interactions. Our results support the hypothesis that absence of an adjacent monomer due to deletion of the hexamerization domain is the most likely cause for disruption of the active site, offering a structural basis for why only the hexameric form of this enzyme is active.

PubMed: 17409150
DOI: 10.1128/JVI.02817-06

Experimental method

X-RAY DIFFRACTION (2.9 Å)