Cell division control in Caulobacter crescentus

Justine Collier

doi:10.1016/j.bbagrm.2018.04.005

Abstract

Caulobacter crescentus is a free-living Alphaproteobacterium that thrives in oligotrophic environments. This review focuses on the regulatory network used by this bacterium to control the levels of cell division proteins, their organization inside the cell and their activity as a function of the cell cycle. Strikingly, C. crescentus makes frequent use of master transcriptional regulators and epigenetic signals, most likely to synchronize cell division with other events of the cell cycle. In addition, cellular metabolism and DNA damage sensors emerge as central players regulating cell division in response to changing environmental conditions.

Highlights

Caulobacter crescentus is a free-living Gram-negative Alphaproteobacterium that lives in oligotrophic aquatic environments such as lakes, rivers or oceans [1]
It always divides asymmetrically into two distinct cell types: a swarmer cell that explores its environment searching for resources, but which cannot replicate itself before it differentiates into the second cell type, called the stalked cell, if conditions are favorable (Fig. 1)
Many of these are conserved in other Alphaproteobacteria [2,55] or even in more distant bacteria [7,50] and C. crescentus just served as a useful model system to discover them or just to confirm their existence

Summary

Introduction

Caulobacter crescentus is a free-living Gram-negative Alphaproteobacterium that lives in oligotrophic aquatic environments such as lakes, rivers or oceans [1]. Recent discoveries showed that the transcription of several cell division genes is regulated by an original epigenetic control mechanism involving the global cell cycle regulator GcrA and the cell cycle-regulated DNA methyltransferase CcrM (Fig. 1) [24] This latter enzyme methylates adenines in 5′-GANTC-3′ motifs, which are enriched in intergenic regions of the C. crescentus chromosome that contain most promoters [25,26]. Consistent with this proposal, it was recently shown that the activity of several GcrA-dependent promoters is modulated by (p) ppGpp levels [33] Overall, this regulatory network is most likely used by C. crescentus to regulate cell division and other events of the cell cycle in response to nitrogen/carbon availability in its natural oligotrophic environments

Post-transcriptional control of cell division proteins

Control of divisome assembly and cytokinesis

Cell size control

Conclusion