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

We also calculated the distribution of κ-values for CTT sequences derived from 1209 distinct orthologs ( Figure 1D) . Given the conservation of the CTP, it follows that the variation in κ is mainly due to sequence variations within the CTL. Roughly 95% of the CTT κ values are within the interval 0.13 < κ < 0.36. The CTT from B. subtilis FtsZ has a κ value of 0.19. The expected distribution of κ values for randomly shuffled sequences that are constrained to have the CTT composition of B. subtilis FtsZ is shifted to lower values when compared to the actual κ values observed for the 1209 orthologous sequences ( Figure S2 ). However, when compared to the shuffled sequences generated in the absence of any selective pressure, many sequences with higher κ values are found, although very few naturally occurring sequences have a κ value above 0.4. This suggests that there is an evolutionary pressure against CTT sequences with κ values that go above 0.4. Similarly, there appears to be a selection pressure against sequences with κ values lower than 0.15.