Biomaterial Database

Substrate Binding Drives Active-Site Closing of Human Blood Group B Galactosyltransferase as Revealed by Hot-Spot Labeling and NMR Spectroscopy Experiments. 2018

Sophie Weissbach, and Friedemann Flügge, and Thomas Peters

Institute of Chemistry, University of Lübeck, Ratzeburger Allee 160, 23562, Lübeck, Germany.

Crystallography has shown that human blood group A (GTA) and B (GTB) glycosyltransferases undergo transitions between "open", "semiclosed", and "closed" conformations upon substrate binding. However, the timescales of the corresponding conformational reorientations are unknown. Crystal structures show that the Trp and Met residues are located at "conformational hot spots" of the enzymes. Therefore, we utilized 15 N side-chain labeling of Trp residues and 13 C-methyl labeling of Met residues to study substrate-induced conformational transitions of GTB. Chemical-shift perturbations (CSPs) of Met and Trp residues in direct contact with substrate ligands reflect binding kinetics, whereas the CSPs of Met and Trp residues at remote sites reflect conformational changes of the enzyme upon substrate binding. Acceptor binding is fast on the chemical-shift timescale with rather small CSPs in the range of less than approximately 20 Hz. Donor binding matches the intermediate exchange regime to yield an estimate for exchange rate constants of approximately 200-300 Hz. Donor or acceptor binding to GTB saturated with acceptor or donor substrate, respectively, is slow (<10 Hz), as are coupled protein motions, reflecting mutual allosteric control of donor and acceptor binding. Remote CSPs suggest that substrate binding drives the enzyme into the closed state required for catalysis. These findings should contribute to better understanding of the mechanism of glycosyl transfer of GTA and GTB.

UI	MeSH Term	Description	Entries
D011485	Protein Binding	The process in which substances, either endogenous or exogenous, bind to proteins, peptides, enzymes, protein precursors, or allied compounds. Specific protein-binding measures are often used as assays in diagnostic assessments.	Plasma Protein Binding Capacity,Binding, Protein
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
D005700	Galactosyltransferases	Enzymes that catalyze the transfer of galactose from a nucleoside diphosphate galactose to an acceptor molecule which is frequently another carbohydrate. EC 2.4.1.-.	Galactosyltransferase
D006801	Humans	Members of the species Homo sapiens.	Homo sapiens,Man (Taxonomy),Human,Man, Modern,Modern Man
D000494	Allosteric Regulation	The modification of the reactivity of ENZYMES by the binding of effectors to sites (ALLOSTERIC SITES) on the enzymes other than the substrate BINDING SITES.	Regulation, Allosteric,Allosteric Regulations,Regulations, Allosteric
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
D062105	Molecular Docking Simulation	A computer simulation technique that is used to model the interaction between two molecules. Typically the docking simulation measures the interactions of a small molecule or ligand with a part of a larger molecule such as a protein.	Molecular Docking,Molecular Docking Simulations,Molecular Docking Analysis,Analysis, Molecular Docking,Docking Analysis, Molecular,Docking Simulation, Molecular,Docking, Molecular,Molecular Docking Analyses,Molecular Dockings,Simulation, Molecular Docking
D019906	Nuclear Magnetic Resonance, Biomolecular	NMR spectroscopy on small- to medium-size biological macromolecules. This is often used for structural investigation of proteins and nucleic acids, and often involves more than one isotope.	Biomolecular Nuclear Magnetic Resonance,Heteronuclear Nuclear Magnetic Resonance,NMR Spectroscopy, Protein,NMR, Biomolecular,NMR, Heteronuclear,NMR, Multinuclear,Nuclear Magnetic Resonance, Heteronuclear,Protein NMR Spectroscopy,Biomolecular NMR,Heteronuclear NMR,Multinuclear NMR,NMR Spectroscopies, Protein,Protein NMR Spectroscopies,Spectroscopies, Protein NMR,Spectroscopy, Protein NMR
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