PomX, a ParA/MinD ATPase activating protein, is a triple regulator of cell division in Myxococcus xanthus

Cell division site positioning is precisely regulated but the underlying mechanisms are incompletely understood. In the social bacterium Myxococcus xanthus, the similar to 15 MDa tripartite PomX/Y/Z complex associates with and translocates across the nucleoid in a PomZ ATPase-dependent manner to directly position and stimulate formation of the cytokinetic FtsZ-ring at midcell, and then undergoes fission during division. Here, we demonstrate that PomX consists of two functionally distinct domains and has three functions. The N-terminal domain stimulates ATPase activity of the ParA/MinD ATPase PomZ. The C-terminal domain interacts with PomY and forms polymers, which serve as a scaffold for PomX/Y/Z complex formation. Moreover, the PomX/PomZ interaction is important for fission of the PomX/Y/Z complex. These observations together with previous work support that the architecturally diverse ATPase activating proteins of ParA/MinD ATPases are highly modular and use the same mechanism to activate their cognate ATPase via a short positively charged N-terminal extension.

Automated summary

The positioning of cell division sites is precisely regulated, but the underlying mechanisms are not completely understood. In the bacterium Myxococcus xanthus, a tripartite PomX/Y/Z complex is responsible for positioning and stimulating the formation of the cytokinetic FtsZ-ring at midcell. The PomX protein has two functionally distinct domains and three functions, playing important roles in the interaction and fission of the PomX/Y/Z complex.