The Saccharomyces cerevisiae SPT8 gene encodes a very acidic protein that is functionally related to SPT3 and TATA-binding protein.
Mutations in the Saccharomyces cerevisiae SPT8 gene were previously isolated as suppressors of retrotransposon insertion mutations in the 5' regions of the HIS4 and LYS2 genes. Mutations in SPT8 confer phenotypes similar to those caused by particular mutations in SPT15, which encodes the TATA-binding protein (TBP). These phenotypes are also similar to those caused by mutations in the SPT3 gene, which encodes a protein that directly interacts with TBP. We have now cloned and sequenced the SPT8 gene and have shown that it encodes a predicted protein of 602 amino acids with an extremely acidic amino terminus. In addition, the predicted SPT8 amino acid sequence contains one copy of a sequence motif found in multiple copies in a number of other eukaryotic proteins, including the beta subunit of heterotrimeric G proteins. To investigate further the relationship between SPT8, SPT3 and TBP, we have analyzed the effect of an spt8 null mutation in combination with different spt3 and spt15 mutations. This genetic analysis has shown that an spt8 deletion mutation is suppressed by particular spt3 alleles. Taken together with previous results, these data suggest that the SPT8 protein is required, directly or indirectly, for TBP function at particular promoters and that the role of SPT8 may be to promote a functional interaction between SPT3 and TBP.
Eisenmann
D M
DM
Department of Genetics, Harvard Medical School, Boston, Massachusetts 02115.
Chapon
C
C
Roberts
S M
SM
Dollard
C
C
Winston
F
F
D000595:Amino Acid Sequence; D001483:Base Sequence; D004251:DNA Transposable Elements; D004268:DNA-Binding Proteins / Q000378:metabolism; D005656:Fungal Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D017353:Gene Deletion; D005800:Genes, Fungal; D008969:Molecular Sequence Data; D016254:Mutagenesis, Insertional; D015183:Restriction Mapping; D012441:Saccharomyces cerevisiae / Q000235:genetics*; D029701:Saccharomyces cerevisiae Proteins; D017422:Sequence Analysis, DNA; D017386:Sequence Homology, Amino Acid; D013489:Suppression, Genetic; D035181:TATA-Box Binding Protein; D014157:Transcription Factors / Q000378:metabolism
D004251:DNA Transposable Elements; D004268:DNA-Binding Proteins; D005656:Fungal Proteins; C075582:SPT3 protein, S cerevisiae; C089445:SPT8 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D035181:TATA-Box Binding Protein; D014157:Transcription Factors