# Structural mechanisms of chromatin assembly

> **NIH NIH R01** · UNIVERSITY OF COLORADO DENVER · 2020 · $487,819

## Abstract

Project Summary
 The packaging of the genome into chromatin that is essential for normal growth, development, and
differentiation has been a focus of the lab for more than 20 years. Nucleosomes are the basic repeating unit of
the chromatin structure that tightly regulates all of the processes that use DNA as a substrate, including
transcription, DNA replication, DNA repair, and recombination. The intricate steps of nucleosome assembly are
guided by histone chaperones that are critical to prevent the aberrant nonspecific interactions of histone
proteins. The key proteins responsible for replication-dependent assembly of nascent histone H3 and H4 are
the H3/H4 histone chaperones, Anti-silencing function 1 (Asf1) and Chromatin Assembly Factor (CAF-1). The
proliferating-cell nuclear antigen (PCNA) targets chromatin assembly to sites of newly replicated DNA. Our
biophysical and structural studies have revealed unexpected, novel and fundamental insights into the early
stages of replication-dependent chromatin assembly, namely the hand-off mechanism involving transfer of
dimers of H3/H4 from Asf1 to CAF-1, and the architectural features of CAF-1 interactions with H3/H4. While
the general functions of these histone chaperones in nucleosome assembly are known, the fundamental
molecular and structural mechanisms for these functions remain obscure. As such, this proposal explores
questions about important and understudied aspects of H3/H4 histone chaperone activity from the recruitment
and mechanism of action at sites of DNA replication which impact the fidelity of epigenetic inheritance as well
as a newly-discovered role in the assembly of single-stranded nucleosomes. To answer these questions,
biophysical and structural approaches, which have been specifically developed to study histone chaperones
will be used together with complementary biochemical and molecular biology approaches in cells. The
outcomes of these studies will be a better understanding of the structural mechanisms involved in the process
of deposition of H3/H4 onto DNA during nucleosome assembly, and these new insights may inform how
chromatin landscapes are established and how the histone chaperones might be manipulated for the purpose
of epigenetic regulation in medical research applications and human disease.

## Key facts

- **NIH application ID:** 9865951
- **Project number:** 1R01GM135604-01
- **Recipient organization:** UNIVERSITY OF COLORADO DENVER
- **Principal Investigator:** MAIR E CHURCHILL
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2020
- **Award amount:** $487,819
- **Award type:** 1
- **Project period:** 2020-02-04 → 2024-01-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/9865951

## Citation

> US National Institutes of Health, RePORTER application 9865951, Structural mechanisms of chromatin assembly (1R01GM135604-01). Retrieved via AI Analytics 2026-05-22 from https://api.ai-analytics.org/grant/nih/9865951. Licensed CC0.

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