Fig. 3
Bioinformatics analysis of Holotrichia parallela PPAE-I. a Schematic representation of H. parallela PPAE-I. Signal peptide (SP) are indicated in green boxes. The disulfide linkages are shown in lines with a symbol (S-S). The position of the peptide bond cleaved during activation is indicated by red arrow. b Sequence analysis of H. parallela PPAE-I. The predicted secretion signal peptide is underlined. The domain divisions (one clip domain and one catalytic domain) are indicated above the sequence. The absolutely conserved Cys residues in clip domain and catalytic domain are numbered and shown in red. Clip domain is predicted to form three disulfide bonds (1–5, 2–4, 3–6). Catalytic domain is also predicted to form three disulfide bonds (7–8, 9–10, 11–12). The residues of the catalytic triad (His155, Asp221, Ser316) are indicated by asterisks. The important determinants of the specificity pocket in the catalytic domain (Asp310, Ser335, G1y357) are marked by black circles. The potential cleavage activation sites are shown in purple and labeled by red arrow. c The overall structure of H. parallela PPAE-I. The N-terminus (N), C-terminus (C), calcium ion and disulfide bridges are labeled. d Surface of H. parallela PPAE-I structure. Substrate binding sites are colored red. e Phylogenetic analysis of H. parallela PPAE-I. The red and green circles highlight H. parallela PPAE-I and the closely homologous specie SP, respectively. Scale bar, 0.05 substitutions per site