# Dynamics and regulation of sister chromosome cohesion in E. coli

> **NIH NIH R01** · BAYLOR COLLEGE OF MEDICINE · 2020 · $49,556

## Abstract

PROJECT SUMMARY/ABSTRACT
Premature arrest of DNA replication forks generates the most severe types of DNA damage that occur in
cells, including DNA double strand breaks and chromosome rearrangements. Genetic change arising from
spontaneous fork arrest is now predicted to exceed that occurring from exogenous sources, and thus is a
major source of the genome instability that causes disease in humans and antibiotic resistance in bacteria.
Despite the potential effects of arrested forks on human health, the root mechanisms that cause and prevent
fork arrest are poorly understood. The long-term goal of this research is to advance our ability to identify and
mitigate the primary causes of replication fork arrest in humans and pathogenic bacteria by establishing a
comprehensive understanding of how, when, and why fork arrest occurs in E. coli. The objective of this
proposal is to determine the dependence of spontaneous replication fork arrest and recovery in E. coli on
local DNA helical strain (supercoiling), and identify the mechanisms that regulate it. The central hypothesis
is that replication fork arrest occurs primarily by a topological mechanism in which DNA helical strain
between the replication fork and bound protein blocks strand unwinding, rather than by direct steric
interference between the replisome and protein. The rationale for this proposal is that understanding the
mechanism of fork arrest is critical, as sterical and topological mechanisms would differ in subsequent effects
and regulation. The objective of this proposal will be achieved through the following specific aims:
(1) Determine the dynamics and genetic requirements of replication fork blockage and restart at DNA-bound
protein complexes. This aim will define the spatial and temporal dynamics of replisome stalling in front of a
barrier, replication protein disassembly, replication fork reversal, and fork restart. Artificial and natural
protein barriers will be examined by whole genome sequencing. (2) Identify mechanisms that promote fork
stability through replication barriers. This aim will be carried out by screening an E. coli overexpression
library for enhanced and retarded replication at an artificial barrier, as well as direct testing of how physical
association of leftward and rightward replisomes (replication factory) affects replication progression through
barriers. (3) Define the relationship between sister chromosome catenation (cohesion), DNA supercoiling,
and replication progression through protein barriers. Preliminary evidence indicates that replisome stalling is
dependent on a build-up of positive supercoils between the fork and protein barrier. Using a novel method to
measure chromosome supercoiling in vivo (PsoraSeq), we will examine how supercoils are diffused along the
chromosome, and whether chromosome catenation behind the fork promotes (or hinders) diffusion of
restrictive supercoils. Our studies will take advantage of a cell synchronization method we devel...

## Key facts

- **NIH application ID:** 10123813
- **Project number:** 3R01GM135368-01S1
- **Recipient organization:** BAYLOR COLLEGE OF MEDICINE
- **Principal Investigator:** David Bates
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2020
- **Award amount:** $49,556
- **Award type:** 3
- **Project period:** 2020-03-01 → 2022-02-28

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10123813

## Citation

> US National Institutes of Health, RePORTER application 10123813, Dynamics and regulation of sister chromosome cohesion in E. coli (3R01GM135368-01S1). Retrieved via AI Analytics 2026-05-26 from https://api.ai-analytics.org/grant/nih/10123813. Licensed CC0.

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