Synergistic effects of substrate-induced conformational changes in phosphoglycerate kinase activation.
Phosphoglycerate kinase (PGK), a key enzyme in glycolysis, catalyses the transfer of a phosphoryl-group from 1,3-bisphosphoglycerate to ADP to form 3-phosphoglycerate and ATP. Despite extensive kinetic and structural investigations over more than two decades, the conformation assumed by this enzyme during catalysis remained unknown. Here we present the 2.8 A crystal structure of a ternary complex of PGK from Trypanosoma brucei, the causative agent of sleeping sickness. This structure determination relied on a procedure in which fragments containing less than 10% of the scattering mass were successively positioned in the unit cell to obtain phases. The PGK ternary complex exhibits a dramatic closing of the large cleft between the two domains seen in all previous studies, thereby bringing the two ligands, 3-phosphoglycerate and ADP into close proximity. Our results demonstrate that PGK is a hinge-bending enzyme, reveal a novel mechanism in which substrate-induced effects combine synergistically to induce major conformational changes and, to our knowledge, afford the first observation of the PGK active site in a catalytic conformation.
Bernstein
B E
BE
Department of Biochemistry, Biomolecular Structure Center, University of Washington, Seattle 98195, USA.
Michels
P A
PA
Hol
W G
WG
D000244:Adenosine Diphosphate / Q000378:metabolism; D000494:Allosteric Regulation; D000818:Animals; D001665:Binding Sites; D002384:Catalysis; D018360:Crystallography, X-Ray; D004789:Enzyme Activation; D004926:Escherichia coli; D005988:Glyceric Acids / Q000378:metabolism; D008958:Models, Molecular; D010735:Phosphoglycerate Kinase / Q000737:chemistry* / Q000378:metabolism; D011487:Protein Conformation; D011994:Recombinant Proteins / Q000737:chemistry; D014346:Trypanosoma brucei brucei / Q000201:enzymology
D005988:Glyceric Acids; D011994:Recombinant Proteins; D000244:Adenosine Diphosphate; C005156:3-phosphoglycerate; D010735:Phosphoglycerate Kinase