2olg
From Proteopedia
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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 , and 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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