Date of Award

2022

Degree Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Graduate Group

Biochemistry & Molecular Biophysics

First Advisor

Shelley L. Berger

Second Advisor

Benjamin A. Garcia

Abstract

Histone acetylation is governed by nuclear acetyl-CoA pools generated in part from local acetate by metabolic enzyme acetyl-CoA synthetase 2 (ACSS2). We hypothesize that during gene activation, a local transfer of intact acetate occurs via sequential action of epigenetic and metabolic enzymes. Using stable isotope labeling, we detect transfer between histone acetylation sites both in vitro using purified mammalian enzymes and in vivo using quiescence exit in Saccharomyces cerevisiae as a change-of-state model. We show that Acs2, the yeast orthologue of ACSS2, is recruited to chromatin during quiescence exit, and observe dynamic histone acetylation changes proximal to Acs2 peaks. We find that Acs2 is preferentially associated with the most upregulated genes, suggesting that acetyl-group transfer plays an important role in gene activation. Overall, our data reveal direct transfer of acetate between histone lysine residues to facilitate rapid transcriptional induction, an exchange that may be critical during changes in nutrient availability.Since ACSS2 does not have known DNA- or histone-binding domains, we hypothesize that it associates with chromatin indirectly through other transcription factors or chromatin modifying enzymes. We performed immunoprecipitation experiments coupled to mass spectrometry in neuronal cell lines and mouse models and identified nuclear accumbens associated 1 (NACC1) as a novel interactor. We determined nuclear localization of both ACSS2 and NACC1 in differentiated cells through proteomics experiments. Moreover, we have found ACSS2 and NACC1 chromatin-bound during differentiation and enriched near genes of cell-cell adherens, cytoplasmic, and membrane, which are important in differentiation and formation of neuronal processes. Our findings highlight a potential mechanism for ACSS2 recruitment to during critical metabolic changes such as neuronal differentiation.

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Biochemistry Commons

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