Figure 3. Patterns of conservation and diversity of interface motifs across septin Groups.

(A) Topology diagram of the GTPase domain secondary structures from N to C-terminus. Conserved GTPase motifs and septin motifs are noted above by black lines (based on Grupp and Gronemeyer 2023) and the NC and G-interacting group regions are noted below by dashed lines (based on Auxier et al 2019). The typical position of the R-finger (when present) is indicated by the pink star. (B) A folded septin monomer. This aggregate depiction includes all predicted domains across eukaryote septins. Relative positions of secondary structures are based on PDB structures 7M6J and 8FWP (Mendonça et al., 2021; Grupp and Gronemeyer, 2023; Marques da Silva et al., 2023). (C) A septin trimer approximating interactions through their G- and NC-interfaces, based on PDB structure 7M6J. Grey stars with pink outline indicate the predicted positions of R-fingers if they are present in the subunits forming an interface. (D) Weblogo representation of select septin motifs, interacting groups, and structural elements across the eukaryotic septin groups. GTPase motifs and septin motifs are depicted above in black, and NC and G-interacting group regions are depicted below in grey. *Note, the location of S1 in groups 6a-8 was determined by relative position in the alignment to the beginning of S2. This loop region which resides between α2 and β4 has considerable sequence length variability and also includes a region where the α3’ helix is predicted.