2b9l

From Proteopedia

Revision as of 14:35, 21 February 2008

Crystal structure of prophenoloxidase activating factor-II from the beetle Holotrichia diomphalia

Overview

Clip-domain serine proteases (SPs) are the essential components of extracellular signaling cascades in various biological processes, especially in embryonic development and the innate immune responses of invertebrates. They consist of a chymotrypsin-like SP domain and one or two clip domains at the N-terminus. Prophenoloxidase-activating factor (PPAF)-II, which belongs to the noncatalytic clip-domain SP family, is indispensable for the generation of the active phenoloxidase leading to melanization, a major defense mechanism of insects. Here, the crystal structure of PPAF-II reveals that the clip domain adopts a novel fold containing a central cleft, which is distinct from the structures of defensins with a similar arrangement of cysteine residues. Ensuing studies demonstrated that PPAF-II forms a homo-oligomer upon cleavage by the upstream protease and that the clip domain of PPAF-II functions as a module for binding phenoloxidase through the central cleft, while the clip domain of a catalytically active easter-type SP plays an essential role in the rapid activation of its protease domain.

About this Structure

2B9L 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 a clip-domain serine protease and functional roles of the clip domains., Piao S, Song YL, Kim JH, Park SY, Park JW, Lee BL, Oh BH, Ha NC, EMBO J. 2005 Dec 21;24(24):4404-14. Epub 2005 Dec 15. PMID:16362048

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