1mbm
From Proteopedia
NSP4 proteinase from Equine Arteritis Virus
Structural highlights
Function[RPOA_EAVBU] The replicase polyprotein 1ab is a multifunctional protein: it contains the activities necessary for the transcription of negative stranded RNA, leader RNA, subgenomic mRNAs and progeny virion RNA as well as proteinases responsible for the cleavage of the polyprotein into functional products.[1] Nsp1 is essential for viral subgenomic mRNA synthesis.[2] Nsp2 cysteine proteinase which cleaves the nsp2/nsp3 site in the polyprotein. Also displays deubiquitinating and deISGylase activities. The deubiquitinating activity cleaves both ubiquitinated and ISGylated products and may therefore regulate ubiquitin and ISG15 dependent host innate immunity.[3] The 3C-like serine proteinase chain is responsible for the majority of cleavages as it cleaves the C-terminus of the polyprotein.[4] The helicase chain, which contains a zinc finger structure, displays RNA and DNA duplex-unwinding activities with 5' to 3' polarity.[5] 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 PubMedArteriviruses are enveloped, positive-stranded RNA viruses and include pathogens of major economic concern to the swine- and horse-breeding industries. The arterivirus replicase gene encodes two large precursor polyproteins that are processed by the viral main proteinase nonstructural protein 4 (nsp4). The three-dimensional structure of the 21-kDa nsp4 from the arterivirus prototype equine arteritis virus has been determined to 2.0 A resolution. Nsp4 adopts the smallest known chymotrypsin-like fold with a canonical catalytic triad of Ser-120, His-39, and Asp-65, as well as a novel alpha/beta C-terminal extension domain that may play a role in mediating protein-protein interactions. In different copies of nsp4 in the asymmetric unit, the oxyanion hole adopts either a collapsed inactive conformation or the standard active conformation, which may be a novel way of regulating proteolytic activity. Structure of arterivirus nsp4. The smallest chymotrypsin-like proteinase with an alpha/beta C-terminal extension and alternate conformations of the oxyanion hole.,Barrette-Ng IH, Ng KK, Mark BL, Van Aken D, Cherney MM, Garen C, Kolodenko Y, Gorbalenya AE, Snijder EJ, James MN J Biol Chem. 2002 Oct 18;277(42):39960-6. Epub 2002 Aug 5. PMID:12163505[6] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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