2olg | pdb_00002olg
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Crystal structure of the serine protease domain of prophenoloxidase activating factor-I in a zymogen form
Overview
A family of serine proteases (SPs) mediates the proteolytic cascades of, embryonic development and immune response in invertebrates. These, proteases, called easter-type SPs, consist of clip and chymotrypsin-like, SP domains. The SP domain of easter-type proteases differs from those of, typical SPs in its primary structure. Herein, we report the first crystal, structure of the SP domain of easter-type proteases, presented as that of, prophenoloxidase activating factor (PPAF)-I in zymogen form. This, structure reveals several important structural features including a bound, calcium ion, an additional loop with a unique disulfide linkage, a, canyon-like deep active site, and an exposed activation loop. We, subsequently show the role of the bound calcium and the proteolytic, susceptibility of the activation loop, which occurs in a clip, domain-independent manner. Based on biochemical study in the presence of, heparin, we suggest that PPAF-III, highly homologous to PPAF-I, contains a, surface patch that is responsible for enhancing the catalytic activity, through interaction with a nonsubstrate region of a target protein. These, results provide insights into an activation mechanism of easter-type, proteases in proteolytic cascades, in comparison with the well studied, blood coagulation enzymes in mammals.
About this Structure
2OLG is a Single protein structure of sequence from Holotrichia diomphalia with NAG, SO4 and CA as ligands. Full crystallographic information is available from OCA.
Reference
Crystal structure of the serine protease domain of prophenoloxidase activating factor-I., Piao S, Kim S, Kim JH, Park JW, Lee BL, Ha NC, J Biol Chem. 2007 Apr 6;282(14):10783-91. Epub 2007 Feb 7. PMID:17287215
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