A novel component of the division‐site selection system of Bacillus subtilis and a new mode of action for the division inhibitor MinCD

Abstract

SummaryCell division in bacteria is governed by a complex cytokinetic machinery in which the key player is a tubulin homologue, FtsZ. Most rod-shaped bacteria divide precisely at mid-cell between segregated sister chromosomes. Selection of the correct site for cell division is thought to be determined by two negative regulatory systems: the nucleoid occlusion system, which prevents division in the vicinity of the chromosomes, and the Min system, which prevents inappropriate division at the cell poles. In Bacillus subtilis recruitment of the division inhibitor MinCD to cell poles depends on DivIVA, and these proteins were thought to be sufficient for Min function. We have now identified a novel component of the division-site selection system, MinJ, which bridges DivIVA and MinD. minJ mutants are impaired in division because MinCD activity is no longer restricted to cell poles. Although MinCD was thought to act specifically on FtsZ assembly, analysis of minJ and divIVA mutants showed that their block in division occurs downstream of FtsZ. The results support a model in which the main function of the Min system lies in allowing only a single round of division per cell cycle, and that MinCD acts at multiple levels to prevent inappropriate division.

The Ser/Thr protein kinase AfsK regulates polar growth and hyphal branching in the filamentous bacteria Streptomyces

“…However, it cannot be excluded that phosphorylation may also influence other aspects of DivIVA behavior, such as its interaction with other proteins or the membrane. The function of B. subtilis DivIVA depends on direct interactions with MinJ and the nucleoid-associated protein RacA (15,43), and the function of S. coelicolor DivIVA is also likely to depend on the direct recruitment of other proteins to the cell poles (5,6). Further, crystal structures of B. subtilis DivIVA show how the oligomers may interact with the membrane via an exposed phenylalanine residue in the highly conserved N-terminal part of the protein (40), and the polar and septal targeting of the B. subtilis DivIVA appears to be explained by a preference of the oligomers for negatively curved membrane surfaces (15,44).…”

Structure and function of bacterial dynamin-like proteins

“…This might be in line with a role of bacterial dynamins in cytokinesis. Indeed, it could be shown that localization of DynA is grossly altered in the absence of MinJ, a cytokinetic protein in B. subtilis (Bramkamp et al , 2008 ;Patrick and Kearns , 2008 ;B ü rmann et al, 2011 ). A dynA null mutation in B. subtilis has, however, no effect on vegetative growth.…”

“…Recently, several membrane integral proteins have been identified that interact with DynA. The cell division proteins MinJ (Bramkamp et al , 2008 ;B ü rmann et al, 2011 ) were shown to be essential for correct localization of DynA, and a bacterial two-hybrid screen identified the uncharacterized membrane protein YneK as the interaction partner of DynA ( B ü rmann et al, 2012 , see below). Thus, one might speculate about a common mecha nism for targeting fusion DLPs to the correct sites on the membranes.…”

Divided we stand: splitting synthetic cells for their proliferation

“…Instead, the MinCD complex is targeted permanently (i.e. without temporal oscillations) to the curved poles, as well as to the highly curved area next to the newly formed septum, by the auxiliary protein MinJ (Patrick and Kearns 2008;Bramkamp et al 2008). MinJ in turn interacts with DivIVA, a protein that was reported to sense negatively curved membranes (Lenarcic et al 2009;Eswaramoorthy et al 2011).…”