Energy Starvation Induces a Cell Cycle Arrest in Escherichia coli by Triggering Degradation of the DnaA Initiator Protein.

Godefroid Charbon,Xiaobo Li,Christopher Campion,Jakob Frimodt-Møller,Peter Ruhdal Jensen,Belén Mendoza-Chamizo,Anders Løbner-Olesen

doi:10.3389/fmolb.2021.629953

Abstract

During steady-state Escherichia coli growth, the amount and activity of the initiator protein, DnaA, controls chromosome replication tightly so that initiation only takes place once per origin in each cell cycle, regardless of growth conditions. However, little is known about the mechanisms involved during transitions from one environmental condition to another or during starvation stress. ATP depletion is one of the consequences of long-term carbon starvation. Here we show that DnaA is degraded in ATP-depleted cells. A chromosome replication initiation block is apparent in such cells as no new rounds of DNA replication are initiated while replication events that have already started proceed to completion.

Highlights

In Escherichia coli, like most other bacteria, chromosome duplication commences only once per cell cycle and at a defined cellular mass
In E. coli, it is well known that stresses that block protein synthesis and growth prevent initiation of chromosome replication
This results from a failure to accumulate the initiator protein DnaA to a level required to trigger initiation as a consequence of growth arrest (Riber and Lobner-Olesen, 2020)

Summary

Introduction

In Escherichia coli, like most other bacteria, chromosome duplication commences only once per cell cycle and at a defined cellular mass. Most regulatory inputs affect the function of the unique origin of replication oriC and/or the initiator protein DnaA (Leonard and Grimwade, 2015; Riber et al, 2016; Katayama et al, 2017; Hansen and Atlung, 2018). The origin of replication is composed of a duplexunwinding region (DUE) and DnaA-oligomerization region (DOR). The DOR harbors recognition sites for DnaA and other regulatory proteins affecting DnaA–oriC structure and function. These include binding sites for nucleoid-associated proteins IHF and Fis, and the oriC methylation/ sequestration proteins Dam/SeqA. Domain III and Domain I are separated by a flexible linker with no apparent regulatory function (Domain II)

Methods

Results

Conclusion