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bioRxiv · 10.1101/2020.10.01.322578

A conserved cell division protein directly regulates FtsZ dynamics in filamentous and unicellular actinobacteria

Schlimpert, S.·Ramos-Leon, F.·Bush, M. J.·McCormick, J. R.·Richardson, J.·Findlay, K.·Sallmen, J. W.
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Abstract

Bacterial cell division is driven by the polymerization of the GTPase FtsZ into a contractile structure, the so-called Z-ring. This essential process involves proteins that modulate FtsZ dynamics and hence the overall Z-ring architecture. Actinobacteria, like Streptomyces and Mycobacterium lack known key FtsZ-regulators. Here we report the identification of SepH, a conserved actinobacterial protein that directly regulates FtsZ dynamics. We show that SepH is crucially involved in cell division in Streptomyces and that it binds FtsZ via a conserved helix-turn-helix motif, stimulating the assembly of FtsZ protofilaments. Comparative in vitro studies using the SepH homolog from Mycobacterium further reveal that SepH can also bundle FtsZ protofilaments, indicating an additional Z-ring stabilizing function in vivo. We propose that SepH plays a crucial role at the onset of cytokinesis in actinobacteria by promoting the rapid assembly of FtsZ filaments into division-competent Z-rings that can go on to mediate septum synthesis.

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Schlimpert, S., Ramos-Leon, F., Bush, M. J., McCormick, J. R., Richardson, J., Findlay, K., Sallmen, J. W.. 2020-10-01. A conserved cell division protein directly regulates FtsZ dynamics in filamentous and unicellular actinobacteria. https://doi.org/10.1101/2020.10.01.322578

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