title: Synergistic action modes of arabinan degradation by exo- and endo-arabinosyl hydrolases.
abstract: Two recombinant arabinosyl hydrolases, α-L-arabinofuranosidase from Geobacillus sp. KCTC 3012 (GAFase) and endo-(1,5)-α-L-arabinanase from Bacillus licheniformis DSM13 (BlABNase), were overexpressed in Escherichia coli, and their synergistic modes of action against sugar beet (branched) arabinan were investigated. Whereas GAFase hydrolyzed 35.9% of L-arabinose residues from sugar beet (branched) arabinan, endo-action of BlABNase released only 0.5% of L-arabinose owing to its extremely low accessibility towards branched arabinan. Interestingly, the simultaneous treatment of GAFase and BlABNase could liberate approximately 91.2% of L-arabinose from arabinan, which was significantly higher than any single exo-enzyme treatment (35.9%) or even stepwise exo- after endo-enzyme treatment (75.5%). Based on their unique modes of action, both exo- and endo-arabinosyl hydrolases can work in concert to catalyze the hydrolysis of arabinan to L-arabinose. At the early stage in arabinan degradation, exo-acting GAFase could remove the terminal arabinose branches to generate debranched arabinan, which could be successively hydrolyzed into arabinooligosaccharides via the endoaction of BlABNase. At the final stage, the simultaneous actions of exo- and endo-hydrolases could synergistically accelerate the L-arabinose production with high conversion yield.
authors.affiliation: Department of Food Science and Biotechnology, and Brain Korea 21 Center for Bio-Resource Development, Chungbuk National University, Cheongju 362-763, Republic of Korea.
authors.forename: Jung-Mi
authors.initials: JM
authors.lastname: Park
authors.forename: Myoung-Uoon
authors.initials: MU
authors.lastname: Jang
authors.forename: Gyo Won
authors.initials: GW
authors.lastname: Oh
authors.forename: Eun-Hee
authors.initials: EH
authors.lastname: Lee
authors.forename: Jung-Hyun
authors.initials: JH
authors.lastname: Kang
authors.forename: Yeong-Bok
authors.initials: YB
authors.lastname: Song
authors.forename: Nam Soo
authors.initials: NS
authors.lastname: Han
authors.forename: Tae-Jip
authors.initials: TJ
authors.lastname: Kim
mesh_terms: D001089:Arabinose / Q000191:economics / Q000378:metabolism*; D001407:Bacillus / Q000201:enzymology; D027461:Beta vulgaris / Q000737:chemistry; D004926:Escherichia coli / Q000235:genetics; D056506:Geobacillus / Q000201:enzymology; D006026:Glycoside Hydrolases / Q000378:metabolism*; D006868:Hydrolysis; D011134:Polysaccharides / Q000378:metabolism*; D011994:Recombinant Proteins / Q000378:metabolism; D013379:Substrate Specificity
chemical_list: D011134:Polysaccharides; D011994:Recombinant Proteins; C030080:araban; D001089:Arabinose; D006026:Glycoside Hydrolases; C019713:alpha-N-arabinofuranosidase; C082526:arabinan endo-1,5-alpha-L-arabinosidase