Synthetic enhancement of a TFIIB defect by a mutation in SSU72, an essential yeast gene encoding a novel protein that affects transcription start site selection in vivo

Zu Wen Sun, Michael Hampsey

Research output: Contribution to journalArticle

69 Scopus citations

Abstract

An ssu72 mutant of Saccharomyces cerevisiae was identified as an enhancer of a TFIIB defect (sua7-1) that confers both a cold-sensitive growth defect and a downstream shift in transcription start site selection. The ssu72-1 allele did not affect cold sensitivity but, in combination with sua7-1, created a heat-sensitive phenotype. Moreover, start site selection at the ADH1 gene was dramatically shifted further downstream of the normal sites. Both of these effects could be rescued by either SUA7 or SSU72, thereby defining a functional relationship between the two genes. SSU72 is a single- copy, essential gene encoding a novel protein of 206 amino acids. The ssu72- 1 allele is the result of a 30-bp duplication creating a sequence encoding a Cys-X2-Cys-X6-Cys-X2-Cys zinc binding motif near the N terminus of Ssu72p. Mutational analysis demonstrated that the N terminus of Ssu72p is essential far function and that cysteine residues in both the normal and mutant proteins are critical. We discuss the possibility that the potential zinc binding motif of Ssu72p facilitates assembly of the transcription preinitiation complex and that this effect is important for accurate start site selection in vivo.

Original languageEnglish (US)
Pages (from-to)1557-1566
Number of pages10
JournalMolecular and cellular biology
Volume16
Issue number4
DOIs
StatePublished - Apr 1996

All Science Journal Classification (ASJC) codes

  • Molecular Biology
  • Cell Biology

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