Abstract

Saccharomyces cerevisiae Yta7 is a barrier active protein that modulates transcriptional states at the silent mating locus, HMR. Additionally, Yta7 regulates histone gene transcription and has overlapping functions with known histone chaperones. This study focused on deciphering the functional role of the noncanonical Yta7 bromodomain. By use of genetic and epistasis analyses, the Yta7 bromodomain was shown to be necessary for barrier activity at HMR and to have overlapping functions with histone regulators (Asf1 and Spt16). Canonical bromodomains can bind to acetylated lysines on histones; however, the Yta7 bromodomain showed an asso-ciation with histones that was independent of posttranslational modification. Further investigation showed that regions of Yta7 other than the bromodomain conferred histone association. Chromatin immunoprecipi-tation-chip analyses revealed that the Yta7 bromodomain was not solely responsible for histone association but was also necessary for proper chromosomal positioning of Yta7. This work demonstrates that the Yta7 bromodomain engages histones for certain cellular functions like barrier chromatin maintenance and partic-ular Spt16/Asf1 cellular pathways of chromatin regulation. Cellular processes such as gene transcription are governed on one level by epigenetics. Chemical modifications occur on chromosomal DNA and proteins to establish a given epige-