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

Delineating the contributions of charge patterning and amino acid composition within CTT sequences: The CTT sequences of all of the designed variants studied to this point have identical amino acid compositions that were derived from the CTT of B. subtilis FtsZ. The parameter κ quantifies the extent of segregation or mixing of oppositely charged residues within the CTT and is agnostic to the specific amino acid composition. In order to separate the contributions from amino acid composition and charge patterning, we designed an FtsZ variant with a WT-like κ for its CTT. However, the amino acid composition was based on a reduced amino acid alphabet. The composition of the CTT was such that all positive charges from the CTL of B. subtilis FtsZ were replaced with Arg, all negatively charged residues were replaced with Glu, Ser / Thr / Cys residues were replaced with Ser, all Asn / Gln residues were replaced with Gln, all hydrophobic groups were replaced with Ala / Val, and the numbers of Gly / Pro residues were kept intact ( Figure 6A) . The FtsZ variant with a reduced alphabet and κ=0.21