Abstract
► There are no fungal septin residues that are universally modified and only a few pairs that are identically modified. ► Posttranslational modifications of septins appear to be evolutionarily recent. ► G domain posttranslational modifications cluster near the G interface, where they probably modulate heteropolymer formation. ► N-terminal and C-terminal modifications are scattered, where they probably modulate unique higher-order structures.
Septins are cytoskeletal elements that contain a highly conserved canonical G domain flanked by more divergent N- and C-termini. Septin monomers form heteropolymers that in turn associate into a variety of higher-order structures. SUMOylation, acetylation and phosphorylation of septins have all been reported; however, there are no examples of residues that are universally modified suggesting that posttranslational modifications of septins evolved relatively recently. Within the conserved G domain, posttranslational modifications cluster in regions near the G interface, consistent with roles in modulating heteropolymer assembly. Within the highly diverged N- and C-termini, posttranslational modifications are scattered randomly, consistent with roles in modulating assembly of higher-order structures that are unique to individual organisms.