Structural insights into recognition of triple-helical beta-glucans by an insect fungal receptor.

ABSTRACT: The innate ability to detect pathogens is achieved by pattern recognition receptors, which recognize non-self-components such as ?1,3-glucan. ?1,3-Glucans form a triple-helical structure stabilized by interchain hydrogen bonds. ?1,3-Glucan recognition protein (?GRP)/gram-negative bacteria-binding protein 3 (GNBP3), one of the pattern recognition receptors, binds to long, structured ?1,3-glucan to initiate innate immune response. However, binding details and how specificity is achieved in such receptors remain important unresolved issues. We solved the crystal structures of the N-terminal ?1,3-glucan recognition domain of ?GRP/GNBP3 (?GRP-N) in complex with the ?1,3-linked glucose hexamer, laminarihexaose. In the crystals, three structured laminarihexaoses simultaneously interact through six glucose residues (two from each chain) with one ?GRP-N. The spatial arrangement of the laminarihexaoses bound to ?GRP-N is almost identical to that of a ?1,3-glucan triple-helical structure. Therefore, our crystallographic structures together with site-directed mutagenesis data provide a structural basis for the unique recognition by such receptors of the triple-helical structure of ?1,3-glucan.

SUBMITTER: Kanagawa M 

PROVIDER: S-EPMC3190723 | biostudies-literature | 2011 Aug

REPOSITORIES: biostudies-literature