A Noncanonical Bromodomain in the AAA ATPase Protein Yta7 Directs Chromosomal Positioning and Barrier Chromatin Activity

University of Arkansas for Medical Sciences, Department of Biochemistry and Molecular Biology, Little Rock, Arkansas 72205, USA.
Molecular and Cellular Biology (Impact Factor: 4.78). 08/2009; 29(17):4604-11. DOI: 10.1128/MCB.00160-09
Source: PubMed


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 association with histones that was independent of posttranslational modification. Further investigation showed that regions of Yta7 other than the bromodomain conferred histone association. Chromatin immunoprecipitation-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 particular Spt16/Asf1 cellular pathways of chromatin regulation.

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Available from: Lauren Blair, Mar 17, 2014
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    • "However, Gradolatto et al. (2008) identified Yta7 as a repressor of the histone genes, and so there is some disagreement here. Yta7 is a putative ATP-dependent remodeling protein containing a bromodomain that binds preferentially to the tail domain of H3 (Gradolatto et al. 2009). However, Yta7 has little effect on histone mRNA levels , and its activities are not confined to the histone genes: it has direct effects on many inducible genes (Lombardi et al. 2011). "
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    • "The noncanonical bromodomain of Yta7 is involved in histone binding, but unlike other bromodomains, binding occurs independently of lysine acetylation (Gradolatto et al. 2009). Elimination of the bromodomain does not completely abolish histone binding; instead, the region of Yta7 with highest affinity for histones lies in its N terminus, which contains the AAA-ATPase domain (Gradolatto et al. 2009). To date, no link between AAA- ATPase function and histone binding has been established. "
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