Fig. 3

Catalytic and βα1 loops of GDPD-like SMaseD/PLDs. (a) Ribbon diagrams of a Sicariid toxin from Loxosceles intermedia (PDB ID 3RLH) and a GDPD from Oleispira antarctica (PDB ID 3QVQ), with βα1 loop (red) and most of the βα2 region (orange) highlighted, as well as C-terminal plug motif (cyan), disulfide bonds (yellow) active site histidines (blue). (b) Partial sequence alignment, including the βα1 loop and catalytic loop (βα2 region), of GDPD-like SMaseD/PLDs filtered at 80% ID. All GDPD-like SMaseD/PLDs have a conserved βα1 loop length that is shorter than the βα1 loop of GDPDs. Catalytic loop of ST-like, AT-like and basal groups is much shorter than the corresponding region in GDPDs, which is an entire small domain (GDPD-I). ST-like and Aquatic have a similar pattern of cysteine residues, but the Aquatic active site loop is longer, variable in length, and has additional cysteine residues