# Mechanisms and Functions of Iron-Sulfur Helicases in DNA repair

> **NIH NIH R01** · UNIVERSITY OF FLORIDA · 2021 · $308,522

## Abstract

PROJECT SUMMARY
DNA damage cannot be prevented because elements in a normal cellular environment including water and
oxygen contribute to damage. Therefore, DNA repair pathways are essential for maintaining genomic stability
and preventing diseases associated with DNA damage-induced mutagenesis. Even with functional DNA repair
pathways, some DNA damage will inevitably escape repair and block DNA replication when encountered by the
replisome. Cells have specialized pathways to bypass or repair DNA damage that blocks replication to allow
replication to proceed. DNA helicases are among the enzymes essential for DNA repair, and these enzymes act
both during and outside of DNA replication. The Rad3/XPD family of iron-sulfur (Fe-S)-containing DNA helicases
plays an important role in DNA repair and maintaining genome stability. There are four family members in
humans, XPD, FANCJ (a.k.a. BRIP1), DDX11 (a.k.a. ChlR1), and RTEL1, that are crucially important for human
health as evidenced by diseases associated with mutations in each of the genes. Genetic disorders linked to
mutations in Rad3/XPD family helicases are typically associated with genome instability, a predisposition to
cancer, and a number of other pathologies. This proposal will define biochemical and molecular mechanisms for
a newly discovered member of the Rad3/XPD helicase family in Escherichia coli, YoaA, that plays a role in
repairing DNA damage during DNA replication. Our collaborators in the Lovett laboratory use 3’-azido-
3’deoxythymidine (AZT) as a reagent to block DNA replication in E. coli, and they identified two genes, yoaA and
holC, that work together to give cells tolerance to AZT. Protein sequence predicts, and our preliminary results
confirm, that the first gene, yoaA, encodes an Fe-S helicase. The second gene, holC, encodes the c subunit of
DNA polymerase III holoenzyme (pol III HE) implicating the E. coli replicase in repair of AZT lesions. However,
our preliminary results have uncovered a novel function for c as a subunit of the YoaA helicase, and we propose
that c functions with the YoaA helicase rather than pol III HE in a pathway that repairs AZT lesions. The main
premise of this proposal is that YoaA and c constitute a DNA helicase that is involved in the repair of
damaged 3’ ends at stalled replication forks. Our aims are to: 1) characterize the YoaA•c protein, 2)
characterize the helicase and substrate preferences for YoaA•c, and 3) define functional interactions between
YoaA and c in vitro and develop a key reagent to investigate these functional interactions in vivo. This proposal
will provide the first biochemical characterization of the YoaA•c helicase, a member of the Rad3/XPD family of
helicases which play critical roles in human health by maintaining genome stability.

## Key facts

- **NIH application ID:** 10096247
- **Project number:** 1R01GM140166-01
- **Recipient organization:** UNIVERSITY OF FLORIDA
- **Principal Investigator:** Linda B Bloom
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2021
- **Award amount:** $308,522
- **Award type:** 1
- **Project period:** 2021-09-23 → 2025-08-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10096247

## Citation

> US National Institutes of Health, RePORTER application 10096247, Mechanisms and Functions of Iron-Sulfur Helicases in DNA repair (1R01GM140166-01). Retrieved via AI Analytics 2026-05-23 from https://api.ai-analytics.org/grant/nih/10096247. Licensed CC0.

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