# Reconstitution and structural dissection of transcription-coupled histone H3.3 deposition

> **NIH NIH F31** · UNIVERSITY OF PENNSYLVANIA · 2020 · $45,520

## Abstract

Project Summary
DNA-histone interactions are at least transiently lost during replication and transcription, which
causes profound change in chromatin structure, and accompanies aging. Thus, efficient
maintenance of chromatin structure during replication and transcription is known to be critical for
cell survival and normal aging. Recently, the H3.3 histone variant has garnered particular interest
in the context of aging because the H3.3 variant accumulates with age and impacts gene
expression. In metazoans, the histone variant H3.3 along with H4 is deposited throughout
transcribed genes by the HUC (HIRA/UBN1/CABIN1) complex, while in ascomycetes, such as
yeast, only one form of histone H3, which shares the same evolutionary ancestry with H3.3 in
metazoans, is deposited by the Hir (Hir1/Hir2/Hir3/Hpc2) complex. Understanding how the Hir
complex functions in yeast will ultimately facilitate the development of therapeutic pathways to
treat the onset of age-associated disease in humans. As my thesis project, I sought a possible
cofactor of the Hir complex in yeast whole cell extract using mass spectrometry, and identified
Spt4/5, a highly-conserved pol II elongation factor required for transcription of nearly all mRNA
genes, which provided first direct evidence of physical interaction between pol II and histone
chaperones for histone deposition. This proposal aims to uncover the molecular basis of Spt4/5
in facilitating histone deposition after passage of transcribing pol II by recruiting the Hir complex.
I expect this study to provide the first molecular evidence of the interplay between histone
deposition and transcription, as well as a first-of-its-kind structural view of its structural basis with
following aims:
 (1) Investigate the functional roles of Spt4/5 in transcription coupled H3/H4 deposition in vitro
 transcription system.
 (2) Determine the molecular basis of the Hir complex in the transcription elongation complex
 via crosslinking mass spectrometry and cryo-EM.

## Key facts

- **NIH application ID:** 10067133
- **Project number:** 1F31AG069390-01
- **Recipient organization:** UNIVERSITY OF PENNSYLVANIA
- **Principal Investigator:** Hee Jong Kim
- **Activity code:** F31 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2020
- **Award amount:** $45,520
- **Award type:** 1
- **Project period:** 2020-09-01 → 2023-08-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10067133

## Citation

> US National Institutes of Health, RePORTER application 10067133, Reconstitution and structural dissection of transcription-coupled histone H3.3 deposition (1F31AG069390-01). Retrieved via AI Analytics 2026-05-23 from https://api.ai-analytics.org/grant/nih/10067133. Licensed CC0.

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