Characterization of the cyr1-2 UGA mutation in Saccharomyces cerevisiae.
cyr1-2 is a temperature-sensitive mutation of the yeast adenylate cyclase structural gene, CYR1. The cyr1-2 mutation has been suggested to be a UGA mutation since a UGA suppressor SUP201 has been isolated as a suppressor of the cyr1-2 mutation. Construction of chimeric genes restricted the region containing the cyr1-2 mutation, and the cyr1-2 UGA mutation was identified at codon 1282, which lies upstream of the region coding for the catalytic domain of adenylate cyclase. Alterations in the region upstream of the cyr1-2 mutation site result in null mutations. The complete open reading frame of the cyr1-2 gene expressed under the control of the GAL1 promoter complemented cyr1-d1 in a galactose-dependent manner. These results suggest that at the permissive temperature weak readthrough occurs at the cyr1-2 mutation site to produce low levels of active adenylate cyclase. An endogenous suppressor in yeast cells is assumed to be responsible for this readthrough.
Morishita
T
T
Institute of Applied Microbiology, University of Tokyo, Japan.
Matsuura
A
A
Uno
I
I
D000262:Adenylyl Cyclases / Q000235:genetics* / Q000378:metabolism; D003062:Codon; D005816:Genetic Complementation Test; D009154:Mutation; D015183:Restriction Mapping; D012441:Saccharomyces cerevisiae / Q000201:enzymology / Q000235:genetics*; D013696:Temperature
D003062:Codon; D000262:Adenylyl Cyclases