His-154 is involved in the linkage of the Saccharomyces cerevisiae L-A double-stranded RNA virus Gag protein to the cap structure of mRNAs and is essential for M1 satellite virus expression.
The coat protein (Gag) of the double-stranded RNA virus L-A was previously shown to form a covalent bond with the cap structure of eukaryotic mRNAs. Here, we identify the linkage as a phosphoroimidazole bond between the alpha phosphate of the cap structure and a nitrogen in the Gag protein His-154 imidazole side chain. Mutations of His-154 abrogate the ability of Gag to bind to the cap structure, without affecting cap recognition, in vivo virus particle formation from an L-A cDNA clone, or in vitro specific binding and replication of plus-stranded single-stranded RNA. However, genetic analyses demonstrate that His-154 is essential for M1 satellite virus expression.
Blanc
A
A
Department of Biochemistry, McGill University, Montréal, Québec, Canada.
Ribas
J C
JC
Wickner
R B
RB
Sonenberg
N
N
D000595:Amino Acid Sequence; D001483:Base Sequence; D015683:Gene Products, gag / Q000096:biosynthesis / Q000302:isolation & purification / Q000378:metabolism*; D006639:Histidine; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D009838:Oligodeoxyribonucleotides; D010957:Plasmids; D012315:RNA Caps / Q000302:isolation & purification / Q000378:metabolism*; D012330:RNA, Double-Stranded / Q000302:isolation & purification / Q000378:metabolism*; D012333:RNA, Messenger / Q000302:isolation & purification / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism*; D013489:Suppression, Genetic; D014779:Virus Replication
D015683:Gene Products, gag; D009838:Oligodeoxyribonucleotides; D012315:RNA Caps; D012330:RNA, Double-Stranded; D012333:RNA, Messenger; D006639:Histidine