Biomaterial Database

Thermus thermophilus glycoside hydrolase family 57 branching enzyme: crystal structure, mechanism of action, and products formed. 2011

Marta Palomo, and Tjaard Pijning, and Thijs Booiman, and Justyna M Dobruchowska, and Jeroen van der Vlist, and Slavko Kralj, and Antoni Planas, and Katja Loos, and Johannis P Kamerling, and Bauke W Dijkstra, and Marc J E C van der Maarel, and Lubbert Dijkhuizen, and Hans Leemhuis

Department of Microbiology, Groningen Biomolecular Sciences and Biotechnology Institute, Kerklaan 30, 9751 NN Haren, The Netherlands.

Branching enzyme (EC 2.4.1.18; glycogen branching enzyme; GBE) catalyzes the formation of α1,6-branching points in glycogen. Until recently it was believed that all GBEs belong to glycoside hydrolase family 13 (GH13). Here we describe the cloning and expression of the Thermus thermophilus family GH57-type GBE and report its biochemical properties and crystal structure at 1.35-Å resolution. The enzyme has a central (β/α)(7)-fold catalytic domain A with an inserted domain B between β2 and α5 and an α-helix-rich C-terminal domain, which is shown to be essential for substrate binding and catalysis. A maltotriose was modeled in the active site of the enzyme which suggests that there is insufficient space for simultaneously binding of donor and acceptor substrates, and that the donor substrate must be cleaved before acceptor substrate can bind. The biochemical assessment showed that the GH57 GBE possesses about 4% hydrolytic activity with amylose and in vitro forms a glucan product with a novel fine structure, demonstrating that the GH57 GBE is clearly different from the GH13 GBEs characterized to date.

UI	MeSH Term	Description	Entries
D011487	Protein Conformation	The characteristic 3-dimensional shape of a protein, including the secondary, supersecondary (motifs), tertiary (domains) and quaternary structure of the peptide chain. PROTEIN STRUCTURE, QUATERNARY describes the conformation assumed by multimeric proteins (aggregates of more than one polypeptide chain).	Conformation, Protein,Conformations, Protein,Protein Conformations
D003001	Cloning, Molecular	The insertion of recombinant DNA molecules from prokaryotic and/or eukaryotic sources into a replicating vehicle, such as a plasmid or virus vector, and the introduction of the resultant hybrid molecules into recipient cells without altering the viability of those cells.	Molecular Cloning
D006026	Glycoside Hydrolases	Any member of the class of enzymes that catalyze the cleavage of the glycosidic linkage of glycosides and the addition of water to the resulting molecules.	Endoglycosidase,Exoglycosidase,Glycohydrolase,Glycosidase,Glycosidases,Glycoside Hydrolase,Endoglycosidases,Exoglycosidases,Glycohydrolases,Hydrolase, Glycoside,Hydrolases, Glycoside
D006868	Hydrolysis	The process of cleaving a chemical compound by the addition of a molecule of water.
D013379	Substrate Specificity	A characteristic feature of enzyme activity in relation to the kind of substrate on which the enzyme or catalytic molecule reacts.	Specificities, Substrate,Specificity, Substrate,Substrate Specificities
D015061	1,4-alpha-Glucan Branching Enzyme	In glycogen or amylopectin synthesis, the enzyme that catalyzes the transfer of a segment of a 1,4-alpha-glucan chain to a primary hydroxy group in a similar glucan chain. EC 2.4.1.18.	Amylopectin Branching Enzyme,Branching Enzyme,Glycogen Branching Enzyme,Q-Enzyme,Branching Glycosyltransferase,Starch Branching Enzyme,1,4 alpha Glucan Branching Enzyme,Branching Enzyme, 1,4-alpha-Glucan,Branching Enzyme, Amylopectin,Branching Enzyme, Glycogen,Branching Enzyme, Starch,Enzyme, 1,4-alpha-Glucan Branching,Enzyme, Amylopectin Branching,Enzyme, Branching,Enzyme, Glycogen Branching,Enzyme, Starch Branching,Glycosyltransferase, Branching,Q Enzyme
D016963	Thermus thermophilus	A species of gram-negative, aerobic, rod-shaped bacteria found in hot springs of neutral to alkaline pH, as well as in hot-water heaters.
D018360	Crystallography, X-Ray	The study of crystal structure using X-RAY DIFFRACTION techniques. (McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed)	X-Ray Crystallography,Crystallography, X Ray,Crystallography, Xray,X Ray Crystallography,Xray Crystallography,Crystallographies, X Ray,X Ray Crystallographies
D020134	Catalytic Domain	The region of an enzyme that interacts with its substrate to cause the enzymatic reaction.	Active Site,Catalytic Core,Catalytic Region,Catalytic Site,Catalytic Subunit,Reactive Site,Active Sites,Catalytic Cores,Catalytic Domains,Catalytic Regions,Catalytic Sites,Catalytic Subunits,Core, Catalytic,Cores, Catalytic,Domain, Catalytic,Domains, Catalytic,Reactive Sites,Region, Catalytic,Regions, Catalytic,Site, Active,Site, Catalytic,Site, Reactive,Sites, Active,Sites, Catalytic,Sites, Reactive,Subunit, Catalytic,Subunits, Catalytic