SSL2, a suppressor of a stem-loop mutation in the HIS4 leader encodes the yeast homolog of human ERCC-3.
Reversion of haploid, His4- yeast containing a stem-loop mutation in the 5' UTR that blocks HIS4 translation initiation identified four unlinked suppressor genes, SSL1-SSL4, which restore His4+ expression. The SSL2 gene encodes an essential 95 kd protein with ATP-dependent helicase motifs. SSL2 protein is 54% identical to the protein encoded by the human gene, ERCC-3, for which a defective form causes xeroderma pigmentosum and Cockayne's syndrome. An SSL2 allele made to resemble the defective ERCC-3 gene confers UV light hypersensitivity to yeast cells. Hence, SSL2 is the functional homolog of ERCC-3. However, the SSL2 suppressor gene does not restore HIS4 expression by removal of the stem-loop from DNA or the mRNA. We propose that SSL2 and ERCC-3 may have two functions, one defined by a UV repair defect, and a second essential function that is related to gene expression.
Gulyas
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KD
Indiana University, Department of Biology, Bloomington 47405.
Donahue
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TF
D000595:Amino Acid Sequence; D001483:Base Sequence; D004265:DNA Helicases / Q000235:genetics*; D004252:DNA Mutational Analysis; D004260:DNA Repair; D004271:DNA, Fungal / Q000235:genetics; D005656:Fungal Proteins / Q000235:genetics*; D005800:Genes, Fungal; D016153:Genes, Suppressor; D006801:Humans; D006860:Hydrogen Bonding; D008969:Molecular Sequence Data; D009838:Oligodeoxyribonucleotides / Q000737:chemistry; D014176:Protein Biosynthesis; D012333:RNA, Messenger / Q000648:ultrastructure; D012441:Saccharomyces cerevisiae / Q000235:genetics*; D029701:Saccharomyces cerevisiae Proteins; D016415:Sequence Alignment; D051758:Transcription Factor TFIIH; D014466:Ultraviolet Rays
D004271:DNA, Fungal; D005656:Fungal Proteins; D009838:Oligodeoxyribonucleotides; D012333:RNA, Messenger; C489575:SSL2 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D051758:Transcription Factor TFIIH; D004265:DNA Helicases