title: Characterization of ApuB, an extracellular type II amylopullulanase from Bifidobacterium breve UCC2003.
abstract: The apuB gene of Bifidobacterium breve UCC2003 was shown to encode an extracellular amylopullulanase. ApuB is composed of a distinct N-terminally located alpha-amylase-containing domain which hydrolyzes alpha-1,4-glucosidic linkages in starch and related polysaccharides and a C-terminally located pullulanase-containing domain which hydrolyzes alpha-1,6 linkages in pullulan, allowing the classification of this enzyme as a bifunctional class II pullulanase. A knockout mutation of the apuB gene in B. breve UCC2003 rendered the resulting mutant incapable of growth in medium containing starch, amylopectin, glycogen, or pullulan as the sole carbon and energy source, confirming the crucial physiological role of this gene in starch metabolism.
authors.affiliation: Department of Microbiology, Alimentary Pharmabiotic Centre and National University of Ireland, Cork, Western Road, Cork, Ireland.
authors.forename: Mary
authors.initials: M
authors.lastname: O'Connell Motherway
authors.forename: Gerald F
authors.initials: GF
authors.lastname: Fitzgerald
authors.forename: Sabine
authors.initials: S
authors.lastname: Neirynck
authors.forename: Sinead
authors.initials: S
authors.lastname: Ryan
authors.forename: Lothar
authors.initials: L
authors.lastname: Steidler
authors.forename: Douwe
authors.initials: D
authors.lastname: van Sinderen
mesh_terms: D000687:Amylopectin / Q000378:metabolism; D001426:Bacterial Proteins / Q000235:genetics* / Q000378:metabolism*; D001644:Bifidobacterium / Q000201:enzymology* / Q000235:genetics / Q000254:growth & development / Q000378:metabolism; D017353:Gene Deletion; D005936:Glucans / Q000378:metabolism; D006003:Glycogen / Q000378:metabolism; D006026:Glycoside Hydrolases / Q000235:genetics* / Q000378:metabolism*; D017434:Protein Structure, Tertiary; D013213:Starch / Q000378:metabolism
chemical_list: D001426:Bacterial Proteins; D005936:Glucans; C009109:pullulan; D013213:Starch; D006003:Glycogen; D000687:Amylopectin; D006026:Glycoside Hydrolases; C082507:amylopullulanase