Fusion of dioxygenase and lignin-binding domains in a novel secreted enzyme from cellulolytic Streptomyces sp. SirexAA-E.

ABSTRACT: Streptomyces sp. SirexAA-E is a highly cellulolytic bacterium isolated from an insect/microbe symbiotic community. When grown on lignin-containing biomass, it secretes SACTE_2871, an aromatic ring dioxygenase domain fused to a family 5/12 carbohydrate-binding module (CBM 5/12). Here we present structural and catalytic studies of this novel fusion enzyme, thus providing insight into its function. The dioxygenase domain has the core β-sandwich fold typical of this enzyme family but lacks a dimerization domain observed in other intradiol dioxygenases. Consequently, the x-ray structure shows that the enzyme is monomeric and the Fe(III)-containing active site is exposed to solvent in a shallow depression on a planar surface. Purified SACTE_2871 catalyzes the O2-dependent intradiol cleavage of c

SUBMITTER: Bianchetti CM 

PROVIDER: S-EPMC3689997 | biostudies-literature | 2013 Jun

REPOSITORIES: biostudies-literature