4UCF

Crystal structure of Bifidobacterium bifidum beta-galactosidase in complex with alpha-galactose

4UCF の概要

• エントリーDOI: 10.2210/pdb4ucf/pdb
• 分子名称: BETA-GALACTOSIDASE, alpha-D-galactopyranose, DI(HYDROXYETHYL)ETHER, ... (5 entities in total)
• 機能のキーワード: hydrolase, lactase, family 42
• 由来する生物種: BIFIDOBACTERIUM BIFIDUM S17
• タンパク質・核酸の鎖数: 3
• 化学式量合計: 233262.01

構造登録者

Godoy, A.S.,Murakami, M.T.,Camilo, C.M.,Bernardes, A.,Polikarpov, I. (登録日: 2014-12-03, 公開日: 2016-01-20, 最終更新日: 2023-12-20)

主引用文献

Godoy, A.S.,Camilo, C.M.,Kadowaki, M.A.,Muniz, H.D.,Santo, M.E.,Murakami, M.T.,Nascimento, A.S.,Polikarpov, I.
Crystal Structure of Beta1-6-Galactosidase from Bifidobacterium Bifidum S17: Trimeric Architecture, Molecular Determinants of the Enzymatic Activity and its Inhibition by Alpha-Galactose.
FEBS J., 283:4097-, 2016

PubMed Abstract: In a search for better comprehension of β-galactosidase function and specificity, we solved the crystal structures of the GH42 β-galactosidase BbgII from Bifidobacterium bifidum S17, a well-adapted probiotic microorganism from the human digestive tract, and its complex with d-α-galactose. BbgII is a three-domain molecule that forms barrel-shaped trimers in solution. BbgII interactions with d-α-galactose, a competitive inhibitor, showed a number of residues that are involved in the coordination of ligands. A combination of site-directed mutagenesis of these amino acid residues with enzymatic activity measurements confirmed that Glu161 and Glu320 are fundamental for catalysis and their substitution by alanines led to catalytically inactive mutants. Mutation Asn160Ala resulted in a two orders of magnitude decrease of the enzyme k without significant modification in its K , whereas mutations Tyr289Phe and His371Phe simultaneously decreased k and increased K values. Enzymatic activity of Glu368Ala mutant was too low to be detected. Our docking and molecular dynamics simulations showed that the enzyme recognizes and tightly binds substrates with β1→6 and β1→3 bonds, while binding of the substrates with β1→4 linkages is less favorable.

PubMed: 27685756
DOI: 10.1111/FEBS.13908

実験手法

X-RAY DIFFRACTION (1.94 Å)