# Molecular dynamics of genome and epigenome integrity in Trypanosoma brucei

> **NIH NIH R01** · RBHS-NEW JERSEY MEDICAL SCHOOL · 2021 · $319,523

## Abstract

PROJECT SUMMARY
 Trypanosoma brucei, the causative pathogen of trypanosomiasis, threatens >60 million people and causes
economic burdens in sub-Saharan Africa. Only a few drugs are available for treating its infection, all with
severe side effects and are difficult to administer. Therefore, identification and characterization of essential
cellular processes with unique features in T. brucei is essential for developing better anti-parasite agents in the
future. DNA replication is essential for cell proliferation and genome integrity. Replication initiation and
elongation must coordinate well with nucleosome disassembly and assembly. Importantly, we have discovered
that simultaneous deletion of region-specific chromatin marks, histone variants H3v and H4v, and a
Kinetoplastid-specific DNA modification, base J, results in severe growth defects. H3vΔ H4vΔ JΔ mutants
exhibit replication stress phenotypes, including formation of nuclear TbRPA1 foci (an indicative of abnormal
exposure of ssDNA resulting from replication stress), and accumulation of G2 cells and cells with incompletely
replicated DNA. Therefore, these chromatin marks are important for proper DNA replication. It is possible that
these chromatin marks influence DNA replication only at loci where they normally reside (local effect). It is also
possible that changes in chromatin structure may affect DNA replication at regions far away on a linear scale
(global effect). In this project, we will test these hypotheses by examining DNA replication at chromosome
internal regions (Aim 1) and telomeres (Aim 2) in H3vΔ H4vΔ JΔ mutants. In Aim 1, we will examine origin firing
profiles and replication elongation (fork migration pattern) by MFA-seq and Repli-seq in Aim 1.1, examine
replication initiation by determining TbORC1 binding at origins in Aim 1.2, determine whether chromatin mark
mutations cause chromosome fragility in Aim 1.3 and/or change transcription profile in Aim 1.5. We will also
determine the 3D chromosome organization to obtain mechanistic understanding of how chromatin marks
control DNA replication inside the nuclear space in Aim 1.4. This will help us to establish logical links between
chromatin structure, DNA replication, and transcription status at the chromosome internal regions. T. brucei
telomeres provide special benefits for studying chromatin structure, replication, and transcription interplay,
because T. brucei subtelomeres are either `highly transcribed and replicated early' or `tightly repressed and
replicated late'. These unique features at telomeres will help us unveil additional mechanistic details on the
interaction among chromatin structure, replication, and transcription. We will study telomere/subtelomere
replication using 2D gel analysis and Chromatin Fiber FISH in Aim 2.1. DNA breaks and recombination will
also be examined in Aim 2.2. From this proposal, we will establish foundation to define how chromatin marks
work together and control replication and transcript...

## Key facts

- **NIH application ID:** 10215251
- **Project number:** 5R01AI127562-07
- **Recipient organization:** RBHS-NEW JERSEY MEDICAL SCHOOL
- **Principal Investigator:** Hee-Sook Kim
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2021
- **Award amount:** $319,523
- **Award type:** 5
- **Project period:** 2017-12-01 → 2023-01-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10215251

## Citation

> US National Institutes of Health, RePORTER application 10215251, Molecular dynamics of genome and epigenome integrity in Trypanosoma brucei (5R01AI127562-07). Retrieved via AI Analytics 2026-05-28 from https://api.ai-analytics.org/grant/nih/10215251. Licensed CC0.

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