# Biochemical, Genetic, and Genomic Analysis of Nucleosome Reorganization by FACT

> **NIH NIH R01** · UTAH STATE HIGHER EDUCATION SYSTEM--UNIVERSITY OF UTAH · 2021 · $343,125

## Abstract

Project Summary/Abstract
This proposal addresses mechanisms used by the histone chaperones FACT and Spt6 to promote assembly,
disassembly, and repair of chromatin. Understanding how chromatin is formed and maintained is central to
understanding regulation of transcription, DNA replication, and repair. The yeast Saccharomyces cerevisiae is
used as a model system that has powerful genetic, biochemical, and genomic tools available to study
fundamental processes common to all eukaryotes. The highly collaborative approach proposed here takes full
advantage of these tools by using a broad range of methods simultaneously. FACT uses multiple histone-
binding domains to convert nucleosomes into an alternative structural form (the reorganized nucleosome) in
which both the DNA and the histones are more accessible. It does this without ATP hydrolysis, distinguishing it
from chromatin remodelers. Reorganization is reversible, so FACT can also assemble nucleosomes out of
loosely associated DNA and histones to construct chromatin. Spt6 also binds histones, DNA, and nucleosomes,
but does not induce reorganization. Comparing the activities and functions of these two chaperones will help
us understand how each of these factors can both block histone interactions and promote them at the
appropriate times, yet each has unique physiological roles that the other cannot perform. FACT has been
viewed as a housekeeping factor that promotes transcription and DNA replication by loosening each
nucleosome encountered to allow polymerases to progress through chromatin. This view has been challenged
and we are in the process of replacing it with a model in which FACT acts to establish and maintain chromatin
in a precisely optimized architecture, and to restore this form after disturbances like transcription or replication.
A key goal of this proposal is to continue challenging the existing model and to contribute to proposing and
testing the new one. Aim 1 addresses questions about what drives the differential localization of FACT and
Spt6, and how they promote or inhibit nucleosome turnover locally to sculpt chromatin structure genome-wide.
Reorganization can promote assembly or disassembly of nucleosomes, but we do not know what the
reorganized form looks like or what influences how it is resolved. Aim 2 examines this using two distinct single
molecule methods in collaborations with the Ha and Studitsky labs, as well as our established and emerging
biochemical assays examining the features of nucleosomes, histones, and chaperones that affect
reorganization. Aim 3 examines the role of the DNA binding module that is common to all FACT complexes,
but whose architecture varies among species. Together these approaches will provide answers to persistent
questions about the mechanisms used by histone chaperones, as well as new questions about their
physiological roles.

## Key facts

- **NIH application ID:** 10126021
- **Project number:** 5R01GM064649-19
- **Recipient organization:** UTAH STATE HIGHER EDUCATION SYSTEM--UNIVERSITY OF UTAH
- **Principal Investigator:** Timothy G Formosa
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2021
- **Award amount:** $343,125
- **Award type:** 5
- **Project period:** 2002-03-01 → 2023-03-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10126021

## Citation

> US National Institutes of Health, RePORTER application 10126021, Biochemical, Genetic, and Genomic Analysis of Nucleosome Reorganization by FACT (5R01GM064649-19). Retrieved via AI Analytics 2026-06-11 from https://api.ai-analytics.org/grant/nih/10126021. Licensed CC0.

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