Structural basis of trypsin inhibition and entomotoxicity of cospin, serine protease inhibitor involved in defense of Coprinopsis cinerea fruiting bodies.

ABSTRACT: Cospin (PIC1) from Coprinopsis cinerea is a serine protease inhibitor with biochemical properties similar to those of the previously characterized fungal serine protease inhibitors, cnispin from Clitocybe nebularis and LeSPI from Lentinus edodes, classified in the family I66 of the MEROPS protease inhibitor classification. In particular, it exhibits a highly specific inhibitory profile as a very strong inhibitor of trypsin with K(i) in the picomolar range. Determination of the crystal structure revealed that the protein has a β-trefoil fold. Site-directed mutagenesis and mass spectrometry results have confirmed Arg-27 as the reactive binding site for trypsin inhibition. The loop containing Arg-27 is positioned between the β2 and β3 strands, distinguishing cospin from other β-trefoil-fold s

SUBMITTER: Sabotic J 

PROVIDER: S-EPMC3281701 | biostudies-literature | 2012 Feb

REPOSITORIES: biostudies-literature