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

Recent studies have shown that the CTT also has a role to play in polymerization and Zring formation, in vitro and in vivo (Buske and Levin, 2013) . Right-angle light scattering is a sensitive method for studying FtsZ polymerization and bundling of FtsZ polymers in the presence of GTP. Outputs from a typical light scattering assay are shown in Figure S4B . In these experiments, the concentration of FtsZ is above the apparent critical threshold for polymerization, which was found to be 2.5 µM in the presence of 50 mM KCl, in a pH 6.5, 50 mM MES buffer (Caplan and Erickson, 2003) . Upon the introduction of 1 mM GTP into the solution mixture, the scattering intensity increases within a narrow time interval and rapidly reaches a steady state value. Light scattering is sensitive to the presence of large aggregates and these might include linear polymers, bundled polymers, or even large spherical assemblies.