The AUG start codon of the Saccharomyces cerevisiae NFS1 gene can be substituted for by UUG without increased initiation of translation at downstream codons.
The selection of the site for initiation of translation for the Saccharomyces cerevisiae NFS1 gene was examined using mutated AUG1, AUG2 and AUG3 codons. When AUG1 of the yeast NFS1 gene was mutated to UUG and the resulting mRNA was translated in vitro using a reticulocyte system, initiation from the mutated codon was abolished and occurred instead at downstream codons at increased rates. When the same mRNA was translated using a yeast extract, translation initiated at the mutated codon, albeit at a reduced rate, and there was no increased translation at downstream AUG codons. The NFS1 gene in which AUG1 was replaced by UUG was also able to substitute for the wild-type gene in vivo in yeast. Western blots confirmed that the encoded protein was the same size as that encoded by the wild-type gene and that both the wild-type and mutated proteins localized to mitochondria. This is apparently the first example of a yeast protein where mutagenesis of AUG1 does not lead to alternate use of a downstream AUG.
Nett
J H
JH
Department of Biochemistry, Dartmouth Medical School, 7200 Vail, Hanover, NH 03755, USA.
Kessl
J
J
Wenz
T
T
Trumpower
B L
BL
D000595:Amino Acid Sequence; D001483:Base Sequence; D018387:Codon, Initiator; D004271:DNA, Fungal; D005656:Fungal Proteins / Q000235:genetics*; D005800:Genes, Fungal; D024101:Mitochondrial Proteins; D008969:Molecular Sequence Data; D014176:Protein Biosynthesis; D012333:RNA, Messenger / Q000235:genetics; D012441:Saccharomyces cerevisiae / Q000737:chemistry / Q000235:genetics*; D029701:Saccharomyces cerevisiae Proteins; D013466:Sulfurtransferases; D014158:Transcription, Genetic
D018387:Codon, Initiator; D004271:DNA, Fungal; D005656:Fungal Proteins; D024101:Mitochondrial Proteins; D012333:RNA, Messenger; D029701:Saccharomyces cerevisiae Proteins; D013466:Sulfurtransferases; C115912:NFS1 protein, S cerevisiae