The N-terminal domain of Drosophila Gram-negative binding protein 3 (GNBP3) defines a novel family of fungal pattern recognition receptors.

ABSTRACT: Gram-negative binding protein 3 (GNBP3), a pattern recognition receptor that circulates in the hemolymph of Drosophila, is responsible for sensing fungal infection and triggering Toll pathway activation. Here, we report that GNBP3 N-terminal domain binds to fungi upon identifying long chains of beta-1,3-glucans in the fungal cell wall as a major ligand. Interestingly, this domain fails to interact strongly with short oligosaccharides. The crystal structure of GNBP3-Nter reveals an immunoglobulin-like fold in which the glucan binding site is masked by a loop that is highly conserved among glucan-binding proteins identified in several insect orders. Structure-based mutagenesis experiments reveal an essential role for this occluding loop in discriminating between short and long polysaccharide

SUBMITTER: Mishima Y 

PROVIDER: S-EPMC2781413 | biostudies-literature | 2009 Oct

REPOSITORIES: biostudies-literature