MAK3 encodes an N-acetyltransferase whose modification of the L-A gag NH2 terminus is necessary for virus particle assembly.
The MAK3 gene is necessary for propagation of the L-A double-stranded RNA virus of Saccharomyces cerevisiae. MAK3 encodes a protein with substantial homology to the Escherichia coli rimI N-acetyltransferase that acetylates the NH2 terminus of ribosomal protein S18, and shares consensus sequences with a group of N-acetyltransferases. The NH2 terminus of the viral major coat protein encoded by L-A is normally blocked, but we find that it is unblocked in a mak3-1 mutant. L-A virus-encoded proteins produced from a cDNA clone of L-A can encapsidate the L-A (+)-strands in a wild-type host, but not in a mak3-1 mutant strain. The amount of major coat protein found in the particle fraction is reduced greater than 100-fold, and the amount in the total cell extract is reduced 5-10-fold. A modified beta-galactosidase, having as its NH2-terminal the NH2-terminal 13 residues of the L-A-encoded major coat protein, is blocked in a wild-type host, but not in a mak3-1 host. We propose that MAK3 encodes an N-acetyltransferase whose modification of the L-A major coat protein NH2 terminus is essential for viral assembly, and that unassembled coat protein is unstable.
Tercero
J C
JC
Section on Genetics of Simple Eukaryotes, National Institute of Diabetes, Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland 20892.
Wickner
R B
RB
D000107:Acetylation; D000595:Amino Acid Sequence; D001191:Arylamine N-Acetyltransferase / Q000235:genetics* / Q000378:metabolism; D001483:Base Sequence; D015152:Blotting, Northern; D015153:Blotting, Western; D002213:Capsid / Q000378:metabolism*; D004279:DNA, Viral; D005656:Fungal Proteins / Q000235:genetics* / Q000378:metabolism; D015683:Gene Products, gag / Q000378:metabolism*; D010957:Plasmids; D012328:RNA Viruses / Q000502:physiology*; D012367:RNA, Viral / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins; D014779:Virus Replication
D004279:DNA, Viral; D005656:Fungal Proteins; D015683:Gene Products, gag; D012367:RNA, Viral; D029701:Saccharomyces cerevisiae Proteins; C077299:MAK3 protein, S cerevisiae; D001191:Arylamine N-Acetyltransferase