In long bacterial cells, the Min system can act off-center.

Abstract

In many rod-shaped bacteria, the Min system is well-known for generating a cell-pole to cell-pole standing wave oscillation with a single node at mid-cell to align cell division. In filamentous E. coli cells, the single-node standing wave transitions into a multi-nodal oscillation. These multi-nodal dynamics have largely been treated simply as an interesting byproduct of artificially elongated cells. However, a recent in vivo study by Muraleedharan et al. shows how multi-nodal Min dynamics are used to align non-mid-cell divisions in the elongated swarmer cells of Vibrio parahaemolyticus. The authors propose a model where the combined actions of cell-length dependent Min dynamics, in concert with nucleoid occlusion along the cell length and regulation of FtsZ levels ensures Z ring formation and complete chromosome segregation at a single off-center position. By limiting the number of cell division events to one per cell at an off-center position, long swarmer cells are preserved within a multiplying population. The findings unveil an elegant mechanism of cell-division regulation by the Min system that allows long swarmer cells to divide without the need to 'dedifferentiate'.