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Structure of TGEV nsp1
Structural highlights
FunctionR1A_CVPPU The papain-like proteinase 1 (PLP1) and papain-like proteinase 2 (PLP2) are responsible for the cleavages located at the N-terminus of the replicase polyprotein. In addition, PLP2 possesses a deubiquitinating/deISGylating activity and processes both 'Lys-48'- and 'Lys-63'-linked polyubiquitin chains from cellular substrates. PLP2 also antagonizes innate immune induction of type I interferon by blocking the nuclear translocation of host IRF-3 (By similarity). The main proteinase 3CL-PRO is responsible for the majority of cleavages as it cleaves the C-terminus of replicase polyprotein at 11 sites. Recognizes substrates containing the core sequence [ILMVF]-Q-|-[SAGC]. Inhibited by the substrate-analog Cbz-Val-Asn-Ser-Thr-Leu-Gln-CMK. Nsp7-nsp8 hexadecamer may possibly confer processivity to the polymerase, maybe by binding to dsRNA or by producing primers utilized by the latter (By similarity). Nsp9 is a ssRNA-binding protein (By similarity). Publication Abstract from PubMedCoronavirus nsp1 have been shown to induce suppression of host mRNA expression and to interfere with host immune response. However, the mechanism is currently unknown. The only available structural information on coronavirus nsp1 is the NMR structure of the N-terminal domain of nsp1 from severe acute respiratory syndrom coronavirus (SARS-CoV) from the genus betacoronavirus. Here we present the first nsp1 structure from an alphacoronavirus, TGEV nsp1. It displays a six-stranded beta-barrel fold with a long alpha helix on the rim of the barrel, a fold shared with SARS-CoV nsp1(13-128). Contrary to previous speculation, the TGEV nsp1 structure suggests that coronavirus nsp1s have a common origin, despite the lack of sequence homology. However, comparisons of surface electrostatics, shape and amino acid conservation between the alpha- and betacoronaviruses lead us to speculate that the mechanism for nsp1 induced suppression of host mRNA expression might be different in these two genera. Structure of alphacoronavirus TGEV nsp1 has implications for coronavirus nsp1 function and evolution.,Jansson AM J Virol. 2012 Dec 26. PMID:23269811[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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