Extragenic suppressors that rescue defects in the heat stress response of the budding yeast mutant tom1.
The TOM1 gene codes for a so-called HECT protein, a putative ubiquitin ligase, in Saccharomyces cerevisiae. Deletion of the entire gene (tom1-10) or the sequence encoding the HECT domain (tom1-2) causes temperature sensitivity for growth. Here we report the isolation of extragenic, recessive suppressors of tom1-2, which were designated tmr (for tom1 revertant) mutations. These were classified into eight complementation groups and six of the genes were identified: tmr1/cyr1, tmnr2/sch9, tmr3/zuo1, tmr4, tmr5/mot1, tmr6/sse1, tmr7 and tmr8/kre6. These results suggested that the tom1 phenotype can be rescued by down-regulating the cAMP/PKA pathway. It was found that the temperature sensitivity of the tom1-2 mutant is indeed suppressed by multiple copies of PDE2 or BCY1, which encode negative regulators of the cAMP/PKA pathway. The MSN2 gene, which encodes a zinc-finger transcription factor involved in the general stress response is also a multicopy suppressor of tom1. It was found that induction levels of both STRE-mediated (general stress response) and HSE-mediated gene expression (heat shock response) upon shift to high temperature are reduced by more than half in the tom1 mutant. Most of the isolated tmr mutations rescued one of the defects seen in both types of heat stress response in the tom1 mutant.
Sasaki
T
T
Department of Biological Sciences, Graduate School of Science, University of Tokyo, Japan.
Toh-e
A
A
Kikuchi
Y
Y
D000242:Cyclic AMP / Q000378:metabolism; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism; D015536:Down-Regulation; D005656:Fungal Proteins / Q000235:genetics / Q000378:metabolism; D015870:Gene Expression; D005800:Genes, Fungal; D018398:Homeodomain Proteins / Q000235:genetics / Q000378:metabolism; D006358:Hot Temperature; D016254:Mutagenesis, Insertional; D009154:Mutation; D010641:Phenotype; D012441:Saccharomyces cerevisiae / Q000235:genetics* / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins; D013489:Suppression, Genetic; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism; D044767:Ubiquitin-Protein Ligases
D004268:DNA-Binding Proteins; D005656:Fungal Proteins; D018398:Homeodomain Proteins; C081935:MSN2 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D014157:Transcription Factors; D000242:Cyclic AMP; C115246:TOM1 protein, S cerevisiae; D044767:Ubiquitin-Protein Ligases; D017868:Cyclic AMP-Dependent Protein Kinases