title: Characterization of the guanine-N7 methyltransferase activity of coronavirus nsp14 on nucleotide GTP.
abstract: Most eukaryotic viruses that replicate in the cytoplasm, including coronaviruses, have evolved strategies to cap their RNAs. In our previous work, the nonstructural protein (nsp) 14 of severe acute respiratory syndrome coronavirus (SARS-CoV) was identified as a cap (guanine-N7)-methyltransferase (N7-MTase). In this study, we found that GTP, dGTP as well as cap analogs GpppG, GpppA and m7GpppG could be methylated by SARS-CoV nsp14. In contrast, the nsp14 could not modify ATP, CTP, UTP, dATP, dCTP, dUTP or cap analog m7GpppA. Critical residues of nsp14 essential for the methyltransferase activity on GTP were identified, which include F73, R84, W86, R310, D331, G333, P335, Y368, C414, and C416. We further showed that the methyltransferase activity of GTP was universal for nsp14 of other coronaviruses. Moreover, the accumulation of m7GTP or presence of protein nsp14 could interfere with protein translation of cellular mRNAs. Altogether, the results revealed a new enzymatic activity of coronavirus nsp14.
authors.affiliation: State Key Laboratory of Virology, College of Life Sciences, Wuhan University, Wuhan 430072, PR China.
authors.forename: Xu
authors.initials: X
authors.lastname: Jin
authors.forename: Yu
authors.initials: Y
authors.lastname: Chen
authors.forename: Ying
authors.initials: Y
authors.lastname: Sun
authors.forename: Cong
authors.initials: C
authors.lastname: Zeng
authors.forename: Yi
authors.initials: Y
authors.lastname: Wang
authors.forename: Jiali
authors.initials: J
authors.lastname: Tao
authors.forename: Andong
authors.initials: A
authors.lastname: Wu
authors.forename: Xiao
authors.initials: X
authors.lastname: Yu
authors.forename: Zhou
authors.initials: Z
authors.lastname: Zhang
authors.forename: Jie
authors.initials: J
authors.lastname: Tian
authors.forename: Deyin
authors.initials: D
authors.lastname: Guo
mesh_terms: D004252:DNA Mutational Analysis; D005095:Exoribonucleases / Q000378:metabolism*; D006160:Guanosine Triphosphate / Q000378:metabolism*; D008780:Methyltransferases / Q000378:metabolism*; D013379:Substrate Specificity; D017361:Viral Nonstructural Proteins / Q000378:metabolism*
chemical_list: D017361:Viral Nonstructural Proteins; D006160:Guanosine Triphosphate; D008780:Methyltransferases; C525596:nsp14 protein, SARS coronavirus; D005095:Exoribonucleases
keywords: AdoMet; Coronavirus; GTP methylation; MTase; RTC; S-adenosyl-l-methionine; SARS; SARS-CoV; Translation; methyltransferase; nonstructural protein; nsp; nsp14; replication and transcription complex; severe acute respiratory syndrome coronavirus