# Mechanistic Studies of Replication Initiation in Prokaryotes

> **NIH NIH R37** · JOHNS HOPKINS UNIVERSITY · 2021 · $444,855

## Abstract

A long-term goal of our research is to understand the molecular mechanisms underlying
the initiation of cellular DNA replication. Initiation is a defining commitment to cell
proliferation; inappropriate onset of replication can lead to genetic instabilities, DNA
damage, and changes in gene copy number. From a biomedical perspective, initiation is
a keystone pathway that should be susceptible to therapeutic intervention for controlling
bacterial infections and cancers; however, a molecular-level understanding of initiation
factors and activities is insufficiently complete to advance such efforts.
The present application focuses on the initiation of DNA replication in bacteria, using E.
coli as a model system. Although a basic framework for this process has been in place
for more than 25 years, its mechanistic principles have remained highly enigmatic. By
employing an innovative mix of structural methods, new biochemical assays, and
analytic technologies, we will answer fundamental questions involving how initiation
proteins collaborate to open a bubble in a replication origin and deposit ring-shaped
helicases onto the DNA. We will determine in molecular detail: 1) how the DnaA
processes the replication origin, oriC, prior to loading of the DnaB helicase and how the
ATPase activity of DnaA controls this activity, 2) how the replicative helicase loader,
DnaC, coordinates ATP turnover and ssDNA binding to efficiently load DnaB onto DNA
and promote helicase-mediated DNA unwinding, and 3) how partner proteins of DnaB
coordinate the transition from helicase recruitment to helicase loading, and how they
regulate different DnaB translocation activities. The outcome of the proposed studies will
be a structural and functional picture of the major steps involved in converting a duplex
chromosomal region into a bidirectional replication fork. These findings in turn will: 1)
define new principles for both the field of DNA replication and the broader action of ATP-
dependent machines and switches, and 2) establish new reagents and assays for
advancing drug-discovery efforts that target initiation systems.

## Key facts

- **NIH application ID:** 10189628
- **Project number:** 5R37GM071747-17
- **Recipient organization:** JOHNS HOPKINS UNIVERSITY
- **Principal Investigator:** James M. Berger
- **Activity code:** R37 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2021
- **Award amount:** $444,855
- **Award type:** 5
- **Project period:** 2005-05-01 → 2022-05-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10189628

## Citation

> US National Institutes of Health, RePORTER application 10189628, Mechanistic Studies of Replication Initiation in Prokaryotes (5R37GM071747-17). Retrieved via AI Analytics 2026-05-22 from https://api.ai-analytics.org/grant/nih/10189628. Licensed CC0.

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