Nucleosomes are comprised of two copies of each of the canonical histones: H2A, H2B, H3, and H4. In Saccharomyces cerevisiae H2A.Z, an H2A variant, replaces canonical histone H2A in about 10% of nucleosomes. Histone H2A.Z has distinct functions from histone H2A and is involved in transcriptional regulation. The antifungal drug rapamycin hinders protein synthesis along with stopping the cell cycle. Since H2A.Z is predicted to participate in transcriptional regulation, it is unsurprising that htz1D strains are sensitive to rapamycin. H2A.Z is found at the promoter of the GTP binding protein Resemblance (GTR1) gene. Indeed, loss of H2A.Z leads transcriptional defects in GTR1 expression. We hypothesized histone H2A.Z plays a role in recruiting RNA polymerase II to the promoter and/or open reading frame of the GTR1 gene. To do this, yeast wild-type, tor1D, htz1D, gtr1D, and htz1/ gtr1 double deletion were grown and a chromatin immunoprecipitation (ChIP) assay was performed. We compared RNA polII levels at the promoters and open reading frame of GTR1 in these mutants.

A second project is studying the gene of unknown function YPR015C in Saccharomyces cerevisiae. Although the genome for S. cerevisiae has been sequenced, there are still many genes that result in proteins with an unknown function such as YPR015C. Based upon bioinformatics data, it is predicted that YPR015C which contains a zinc finger is a transcription factor. YPR015C is localized to the nucleus and chromatin which supports the hypothesis that it is a transcription factor. In order to confirm that YPR015C is localized to the nucleus, it was planned to use green fluorescent protein (GFP) tagged YPR015C along with DAPI stain which binds to chromatin to show localization of YPR015C.

Grace Tepes

Appearances