Structure-function analysis of grass clip serine protease involved in Drosophila Toll pathway activation.

ABSTRACT: Grass is a clip domain serine protease (SP) involved in a proteolytic cascade triggering the Toll pathway activation of Drosophila during an immune response. Epistasic studies position it downstream of the apical protease ModSP and upstream of the terminal protease Spaetzle-processing enzyme. Here, we report the crystal structure of Grass zymogen. We found that Grass displays a rather deep active site cleft comparable with that of proteases of coagulation and complement cascades. A key distinctive feature is the presence of an additional loop (75-loop) in the proximity of the activation site localized on a protruding loop. All biochemical attempts to hydrolyze the activation site of Grass failed, strongly suggesting restricted access to this region. The 75-loop is thus proposed to constitu

SUBMITTER: Kellenberger C 

PROVIDER: S-EPMC3069433 | biostudies-literature | 2011 Apr

REPOSITORIES: biostudies-literature