Intrinsic characteristics of Min proteins on the cell division ofHelicobacter pylori

Abstract

Helicobacter pylori divides in the human stomach resulting in persistent infections and causing various disorders. Bacterial cell division is precisely coordinated by many molecules, including FtsZ and Min proteins. However, the role of Min proteins in H. pylori division is poorly understood. We investigated the functional characteristics of Min proteins in wild-type HPK5 and five HPK5-derivative mutants using morphological and genetic approaches. All mutants showed a filamentous shape. However, the bacterial cell growth and viability of three single-gene mutants (minC, minD, minE) were similar to that of the wild-type. The coccoid form number was lowest in the minE-disruptant, indicating that MinE contributes to the coccoid form conversion during the stationary phase. Immunofluorescence microscopic observations showed that FtsZ was dispersedly distributed throughout the bacterial cell irrespective of nucleoid position in only minD-disruptants, indicating that MinD is involved in the nucleoid occlusion system. A chase assay demonstrated that MinC loss suppressed FtsZ-degradation, indicating that FtsZ degrades in a MinC-dependent manner. Molecular interactions between FtsZ and Min proteins were confirmed by immunoprecipitation (IP)-western blotting (WB), suggesting the functional cooperation of these molecules during bacterial cell division. This study describes the intrinsic characteristics of Min proteins and provides new insights into H. pylori cell division.

Morphology of Helicobacter pylori as a result of peptidoglycan and cytoskeleton rearrangements

“…During the later stages of cell division, MinE gradually displaces MinCD from the cell membrane, leading to a transfer of MinC and MinD subunits to the opposite cell pole. This action is accompanied by a new polar MinCD localisation, inhibition of the FtsZ-dependent division, and separation of a daughter cell [ 57 , 59 ]. The complex of Mre-like proteins is called elongasome, and in H. pylori it consists of two components: MreB and MreC.…”

“…FtsZ is a tubulin homologue [ 12 , 51 , 54 , 57 ]. This protein localising at the site of septation forms a Z-ring and polymerises in linear protofilaments in a GTP-dependent manner recruiting other proteins (e.g.…”

“…FtsA, ZipA, and ZapA) associated with cell division and peptidoglycan remodelling, referred to as the divisome. In H. pylori most of these proteins are absent, while Min proteins are responsible for the coordination of FtsZ functioning [ 57 ] ( Figure 2 ). In most bacteria the Min protein system consists of MinC, MinD, and MinE [ 58 ].…”

“…the formation of filamentous cells in Δ minE mutants and creation of mini cells in minE over-expressing microbes. In H. pylori a different mechanism is observed because the deletion of any of the genes ( minC , minD, and/ or minE ) leads to filamentous cell formation [ 57 ]. It is concluded that MinCD in H. pylori are responsible for the process of proper cell division, affecting FtsZ assembly and/ or Z-ring conformation [ 57 , 59 ].…”

“…In H. pylori a different mechanism is observed because the deletion of any of the genes ( minC , minD, and/ or minE ) leads to filamentous cell formation [ 57 ]. It is concluded that MinCD in H. pylori are responsible for the process of proper cell division, affecting FtsZ assembly and/ or Z-ring conformation [ 57 , 59 ]. MinE, in turn, may play a role in morphological transformation into a coccoidal form, because Δ minE mutants presented an extremely low number of spherical forms [ 57 ].…”