The PI3K domain of Tra1 is required for transcriptional regulation

Tra1 is an essential component of the S. cerevisiae SAGA and NuA4 complexes. Using targeted mutagenesis, we identified residues within its C-terminal phosphatidylinositol-3 kinase (PI3K) domain that are required for function. The phenotype of tra1-P3408A, S3463A and SRR3413-3415AAA included temperature sensitivity and reduced growth in media containing 6% ethanol or aminotriazole. These alleles resulted in ≥2-fold change in expression of ~7% of yeast genes in rich media and reduced activation of PHO5 and ADH2 promoters. Tra1-SRR3413 associated with components of both the NuA4 and SAGA complexes and with the Gal4 transcriptional activation domain similar to wild-type protein. Tra1-SRR3413 resulted in a decreased ratio of acetylated histone H3 and H4 to total histone H3 at the PHO5 promoter that appeared largely due to increased unacetylated histone. Slow growth of a tra1-SRR3413 strain in aminotriazole was suppressed by deletion of Vps1 and the Vps1 interacting protein, Rad16. In addition, ethanol sensitivity was suppressed by loss of Vam3, suggesting that Tra1 is involved with protein trafficking and membrane sorting. Furthermore, tra1-SRR3413 results in generation dependent telomere shortening. While the tra1 alleles have some phenotypic similarities with deletions of SAGA and/or NuA4 components, the pattern of gene expression, genetic interactions and telomere shortening suggest possible novel functions for the PI3K-domain of Tra1. Keywords: yeast, Tra1, PI3-kinase domain, gene expression, genetic modification Two dye-swapped, biological replicate experiments were performed for yeast strains CY1507(TRA1::Tn10LUK with 1643(myc-tra1_P3408A-YCplac111)), CY1531(TRA1::Tn10LUK with 1644(myc-tra1_SRR3413-YCplac111)) and CY1514(TRA1::Tn10LUK with 1688(myc-tra1_S3463A-YCplac111)) with reference to CY1524(TRA1::Tn10LUK with 1614(myc-TRA1_SB-YCplac111)).