Evolved sequence features within the intrinsically disordered tail influence FtsZ assembly and bacterial cell division

Megan C. Cohan; Ammon E. Posey; Steven J. Grigsby; Anuradha Mittal; Alex S. Holehouse; Paul J. Buske; Petra A. Levin; Rohit V. Pappu

Deletion of the FtsZ CTT leads to a 3-fold increase in GTPase activity. Thus, the CTT plays an auto-inhibitory role by promoting polymerization and lowering the efficiency of GTP hydrolysis. In this way, although GTP binding is required to promote canonical FtsZ polymerization, the hydrolysis of GTP provides the energy required to bend / deform FtsZ polymers to form Z-rings. Preliminary atomistic simulations of the CTT tethered to the FtsZ core show that the CTP motif makes fluctuating patterns of contacts with the T7 activation loop of the FtsZ core (data not shown). We propose that in addition to stabilizing the protofilaments and reducing subunit turnover by lowering the GTPase activity, the CTL may also enable inhibitory interactions between the CTP and the active site of the enzyme. This auto-inhibition could further reduce the GTPase activity and promote polymerization by weakening the dissociation of FtsZ subunits. Similar auto-inhibitory roles have been ascribed to disordered tails that are tethered to ordered domains in a range of different systems (Trudeau et al., 2013) .