alexa Structure and Catalytic Mechanism of a Glycoside Hydrolase Family-127 and#946;-L-Arabinofuranosidase (HypBA1) | OMICS International | Abstract
ISSN: 2155-9821

Journal of Bioprocessing & Biotechniques
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Research Article

Structure and Catalytic Mechanism of a Glycoside Hydrolase Family-127 β-L-Arabinofuranosidase (HypBA1)

Chun-Hsiang Huang1, Zhen Zhu1, Ya-Shan Cheng2,3, Hsiu-Chien Chan1, Tzu-Ping Ko4, Chun-Chi Chen1, Iren Wang4, Meng-RuHo4, Shang-Te Danny Hsu4,6, Yi-Fang Zeng7, Yu-Ning Huang7, Je-Ruei Liu5,7,8*and Rey-Ting Guo1*
1Industrial Enzymes National Engineering Laboratory, Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences, Tianjin 300308, China
2Genozyme Biotechnology Inc., Taipei 106, Taiwan
3AsiaPac Biotechnology Co., Ltd., Dongguan 523808, China
4Institute of Biological Chemistry, Taiwan
5Agricultural Biotechnology Research Center, Academia Sinica, Taipei 115, Taiwan
6Institute of Biochemical Sciences, Taiwan
7Institute of Biotechnology, Taiwan
8Department of Animal Science and Technology, National Taiwan University, Taipei 106, Taiwan
Corresponding Authors : Rey-Ting Guo
Industrial Enzymes National Engineering Laboratory
Tianjin Institute of Industrial Biotechnology
Chinese Academy of Sciences, Tianjin 300308, China
Tel: 86-022-84861999
Fax :86 - 022-24828701
E-mail: [email protected]
  Je-Ruei Liu
Department of Animal Science and Technology
National Taiwan University
Taipei 106, Taiwan
Tel: 886-2-3366-6011
Fax: 886-2-3366-6001
E-mail: [email protected]
Received June 28, 2014; Accepted July 23, 2014; Published August 03, 2014
Citation: Huang CH, Zhu Z, Cheng YS, Chan HC, Ko TP, et al. (2014) Structure and Catalytic Mechanism of a Glycoside Hydrolase Family-127 ß-LArabinofuranosidase (HypBA1). J Bioprocess Biotech 4:171 doi: 10.4172/2155-9821.1000171
Copyright: ©2014 Huang CH, et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.


The β-L-arabinofuranosidase from Bifidobacterium longum JCM 1217 (HypBA1), a DUF1680 family member, was recently characterized and classified to the glycoside hydrolase family 127 (GH127) by CAZy. The HypBA1 exerts exo-glycosidase activity to hydrolyze β-1,2-linked arabinofuranose disaccharides from non-reducing end into individual L-arabinoses. In this study, the crystal structures of HypBA1 and its complex with L-arabinose and Zn2+ ion were determined at 2.23-2.78 Å resolution. HypBA1 consists of three domains, denoted N-, S- and C-domain. The N-domain (residues 1-5 and 434-538) and C-domain (residues 539-658) adopt β-jellyroll architectures, and the S-domain (residues 6-433) adopts an (α/α)6-barrel fold. HypBA1 utilizes the S- and C-domain to form a functional dimer. The complex structure suggests that the catalytic core lies in the S-domain where Cys417 and Glu322 serve as nucleophile and general acid/base, respectively, to cleave the glycosidic bonds via a retaining mechanism. The enzyme contains a restricted carbohydrate-binding cleft, which accommodates shorter arabino oligosaccharides exclusively. In addition to the complex crystal structures, we have one more interesting crystal which contains the apo HypBA1 structure without Zn2+ ion. In this structure, the Cys417-containing loop is shifted away due to the disappearance of all coordinate bonds in the absence of Zn2+ ion. Cys417 is thus diverted from the attack position, and probably is also protonated, disabling its role as the nucleophile. Therefore, Zn2+ ion is indeed involved in the catalytic reaction through maintaining the proper configuration of active site. Thus the unique catalytic mechanism of GH127 enzymes is now well elucidated.