title: A multifunctional hybrid glycosyl hydrolase discovered in an uncultured microbial consortium from ruminant gut.
abstract: A unique multifunctional glycosyl hydrolase was discovered by screening an environmental DNA library prepared from a microbial consortium collected from cow rumen. The protein consists of two adjacent catalytic domains. Sequence analysis predicted that one domain conforms to glycosyl hydrolase family 5 and the other to family 26. The enzyme is active on several different beta-linked substrates and possesses mannanase, xylanase, and glucanase activities. Site-directed mutagenesis studies on the catalytic residues confirmed the presence of two functionally independent catalytic domains. Using site-specific mutations, it was shown that one catalytic site hydrolyzes beta-1,4-linked mannan substrates, while the second catalytic site hydrolyzes beta-1,4-linked xylan and beta-1,4-linked glucan substrates. Polysaccharide Analysis using Carbohydrate gel Electrophoresis (PACE) also confirmed that the enzyme has discrete domains for binding and hydrolysis of glucan- and mannan-linked polysaccharides. Such multifunctional enzymes have many potential industrial applications in plant processing, including biomass saccharification, animal feed nutritional enhancement, textile, and pulp and paper processing.
authors.affiliation: Diversa Corporation, 4955 Directors Place, San Diego, CA 92121, USA.
authors.forename: Nisha
authors.initials: N
authors.lastname: Palackal
authors.forename: Christopher S
authors.initials: CS
authors.lastname: Lyon
authors.forename: Seema
authors.initials: S
authors.lastname: Zaidi
authors.forename: Peter
authors.initials: P
authors.lastname: Luginbühl
authors.forename: Paul
authors.initials: P
authors.lastname: Dupree
authors.forename: Florence
authors.initials: F
authors.lastname: Goubet
authors.forename: John L
authors.initials: JL
authors.lastname: Macomber
authors.forename: Jay M
authors.initials: JM
authors.lastname: Short
authors.forename: Geoffrey P
authors.initials: GP
authors.lastname: Hazlewood
authors.forename: Dan E
authors.initials: DE
authors.lastname: Robertson
authors.forename: Brian A
authors.initials: BA
authors.lastname: Steer
mesh_terms: D000818:Animals; D001483:Base Sequence; D002417:Cattle; D015723:Gene Library; D005936:Glucans / Q000378:metabolism; D006026:Glycoside Hydrolases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D007218:Industrial Microbiology; D008351:Mannans / Q000378:metabolism; D008969:Molecular Sequence Data; D009097:Multienzyme Complexes / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D016297:Mutagenesis, Site-Directed; D012417:Rumen / Q000382:microbiology*; D017422:Sequence Analysis, DNA; D014990:Xylans / Q000378:metabolism
chemical_list: D005936:Glucans; D008351:Mannans; D009097:Multienzyme Complexes; D014990:Xylans; D006026:Glycoside Hydrolases