Glycoside hydrolase family 3 (GH3) beta-glucosidases (BGLs) from filamentous fungi have been widely and commercially used for supplementation of cellulases. BGL from the fungus Aspergillus aculeatus (AaBGL1) belongs to GH3 and shows high activity toward cellooligosaccharides up to high degree of polymerization. Here we determined the crystal structure of AaBGL1. In addition to the substrate-free structure, complex structures with glucose and various inhibitors were determined. The AaBGL1 structure is highly glycosylated with 88 monosaccharides (18 N-glycan chains) in the dimer. The largest N-glycan chain comprises 10 monosaccharides and is one of the largest glycans ever observed in protein crystal structures. A prominent insertion region exists in a fibronectin type III domain, and this region extends to cover a wide surface area of the enzyme. The subsite +1 of AaBGL1 is highly hydrophobic. Three aromatic residues are involved in the subsite +1 and located in short loop regions that are uniquely present in this enzyme. There is a long cleft extending from the subsite +1, which appears to be suitable for binding long cellooligosaccharides. The crystal structures of AaBGL1 will provide an important structural basis for the technical improvement of enzymatic cellulosic biomass conversion.
Crystal Structures of Glycoside Hydrolase Family 3 beta-Glucosidase 1 from Aspergillus aculeatus.,Suzuki K, Sumitani JI, Nam YW, Nishimaki T, Tani S, Wakagi T, Kawaguchi T, Fushinobu S Biochem J. 2013 Mar 28. PMID:23537284
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
↑ Suzuki K, Sumitani JI, Nam YW, Nishimaki T, Tani S, Wakagi T, Kawaguchi T, Fushinobu S. Crystal Structures of Glycoside Hydrolase Family 3 beta-Glucosidase 1 from Aspergillus aculeatus. Biochem J. 2013 Mar 28. PMID:23537284 doi:10.1042/BJ20130054