Purification, Cloning, Functional Expression, Structure, and Characterization of a Thermostable β-Mannanase from B168 and Its Efficiency in Production of Mannooligosaccharides from Coffee Wastes.

Highly thermostable β-mannanase, belonging to glycoside hydrolase family 5 subfamily 7, was purified from the culture supernatant of B168 and the cDNA of its transcript was cloned. The recombinant enzyme showed maximal activity at pH 4.5 and 85 °C.

Crystal structure and characterization of the glycoside hydrolase family 62 α-L-arabinofuranosidase from Streptomyces coelicolor.

α-L-arabinofuranosidase, which belongs to the glycoside hydrolase family 62 (GH62), hydrolyzes arabinoxylan but not arabinan or arabinogalactan. The crystal structures of several α-L-arabinofuranosidases have been determined, although the structures, catalytic mechanisms, and substrate specificities of GH62 enzymes remain unclear. To evaluate the substrate specificity of a GH62 enzyme, we determined the crystal structure of α-L-arabinofuranosidase, which comprises a carbohydrate-binding module family 13 domain at its N terminus and a catalytic domain at its C terminus, from Streptomyces coelicolor.

The structure of a Streptomyces avermitilis α-L-rhamnosidase reveals a novel carbohydrate-binding module CBM67 within the six-domain arrangement.

α-L-rhamnosidases hydrolyze α-linked L-rhamnosides from oligosaccharides or polysaccharides. We determined the crystal structure of the glycoside hydrolase family 78 Streptomyces avermitilis α-L-rhamnosidase (SaRha78A) in its free and L-rhamnose complexed forms, which revealed the presence of six domains N, D, E, F, A, and C. In the ligand complex, L-rhamnose was bound in the proposed active site of the catalytic module, revealing the likely catalytic mechanism of SaRha78A.

Characterization of an endo-processive-type xyloglucanase having a β-1,4-glucan-binding module and an endo-type xyloglucanase from Streptomyces avermitilis.

We cloned two glycoside hydrolase family 74 genes, the sav_1856 gene and the sav_2574 gene, from Streptomyces avermitilis NBRC14893 and characterized the resultant recombinant proteins. The sav_1856 gene product (SaGH74A) consisted of a catalytic domain and a family 2 carbohydrate-binding module at the C terminus, while the sav_2574 gene product (SaGH74B) consisted of only a catalytic domain. SaGH74A and SaGH74B were expressed successfully and had molecular masses of 92 and 78 kDa, respectively.

Structural and biochemical characterization of glycoside hydrolase family 79 β-glucuronidase from Acidobacterium capsulatum.

We present the first structure of a glycoside hydrolase family 79 β-glucuronidase from Acidobacterium capsulatum, both as a product complex with β-D-glucuronic acid (GlcA) and as its trapped covalent 2-fluoroglucuronyl intermediate. This enzyme consists of a catalytic (β/α)(8)-barrel domain and a β-domain with irregular Greek key motifs that is of unknown function. The enzyme showed β-glucuronidase activity and trace levels of β-glucosidase and β-xylosidase activities.