title: Mutational effects of the consensus aromatic residues in the mRNA capping domain of Bamboo mosaic virus on GTP methylation and virus accumulation.
abstract: RNA viruses classified in the alphavirus-like superfamily possess a distinct capping domain, catalyzing GTP methylation and subsequent transfer of the m(7)GMP moiety from m(7)GTP to the 5'-diphosphate end of viral RNA. The H68A mutation in the capping domain of Bamboo mosaic virus enhanced GTP methylation but disabled the following transguanylation, making it possible to characterize the enzyme's methyltransferase activity separately. To explore the involvement of aromatic amino acids in substrate recognition, consensus aromatic residues in the viral domain were subjected to mutational analysis in the background of H68A. Several residues, including Y126, F144, F161, Y192, Y203, Y213, and W222, were found to be critical for GTP methylation and S-adenosylmethionine (AdoMet) binding. These mutations, except for Y213, also adversely affected the GTP binding, but less extensively. In general, the mutations decreasing the activity for GTP methylation also had correspondingly detrimental effects on virus accumulation.
authors.affiliation: Graduate Institute of Biotechnology, National Chung Hsing University, 250 Kuo-Kuang Rd, Taichung, Taiwan 40227, ROC.
authors.forename: Rei-Hsing
authors.initials: RH
authors.lastname: Hu
authors.forename: Mei-Chun
authors.initials: MC
authors.lastname: Lin
authors.forename: Yau-Heiu
authors.initials: YH
authors.lastname: Hsu
authors.forename: Menghsiao
authors.initials: M
authors.lastname: Meng
mesh_terms: D019943:Amino Acid Substitution; D006160:Guanosine Triphosphate / Q000378:metabolism*; D008745:Methylation; D008780:Methyltransferases / Q000235:genetics / Q000378:metabolism*; D016297:Mutagenesis, Site-Directed; D050505:Mutant Proteins / Q000235:genetics / Q000378:metabolism; D020125:Mutation, Missense; D017863:Potexvirus / Q000235:genetics / Q000502:physiology*; D012315:RNA Caps / Q000378:metabolism*; D012367:RNA, Viral / Q000378:metabolism*; D014764:Viral Proteins / Q000235:genetics / Q000378:metabolism*; D014779:Virus Replication
chemical_list: D050505:Mutant Proteins; D012315:RNA Caps; D012367:RNA, Viral; D014764:Viral Proteins; D006160:Guanosine Triphosphate; D008780:Methyltransferases