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

Sequence-intrinsic conformational preferences of CTT sequences are influenced by the extent of charge segregation: We performed atomistic simulations of the WT CTT from B. subtilis FtsZ and the six designed variants. We used the ABSINTH implicit solvation model and forcefield paradigm (Vitalis and Pappu, 2009a; Vitalis and Pappu, 2009b) for these simulations. The results were used to quantify the impact of charge patterning on the overall sizes, shapes, and amplitudes of conformational fluctuations of CTT sequences modeled as autonomous units. As κ increases, there is a clear trend toward compaction. We quantified the preference for compact structures in terms of the length normalized mean radii of gyration R g n that are plotted for the WT CTT and designed variants ( Figure 2C ). For each variant, R g n is calculated as the mean R g value of the variant divided by the square root of the number of residues n in the CTT. Variants of the B. subtilis CTT sequence with κ values that are lower than the WT are slightly more expanded than the WT CTT, although the degree of expansion is not statistically significant. However, sequences with κ values that are higher than the WT become increasingly more compact with increasing κ. It follows, in accord with previous observations for other systems (Das et al., 2016; Das and Pappu, 2013; Sherry et al., 2017) , All rights reserved. No reuse allowed without permission.