title: Complete catalytic cycle of cofactor-independent phosphoglycerate mutase involves a spring-loaded mechanism.
abstract: Cofactor-independent phosphoglycerate mutase (iPGM), an important enzyme in glycolysis and gluconeogenesis, catalyses the isomerization of 2- and 3-phosphoglycerates by an Mn(2+)-dependent phospho-transfer mechanism via a phospho-enzyme intermediate. Crystal structures of bi-domain iPGM from Staphylococcus aureus, together with substrate-bound forms, have revealed a new conformation of the enzyme, representing an intermediate state of domain movement. The substrate-binding site and the catalytic site are present in two distinct domains in the intermediate form. X-ray crystallography complemented by simulated dynamics has enabled delineation of the complete catalytic cycle, which includes binding of the substrate, followed by its positioning into the catalytic site, phospho-transfer and finally product release. The present work describes a novel mechanism of domain movement controlled by a hydrophobic patch that is exposed on domain closure and acts like a spring to keep the protein in open conformation. Domain closing occurs after substrate binding, and is essential for phospho-transfer, whereas the open conformation is a prerequisite for efficient substrate binding and product dissociation. A new model of catalysis has been proposed by correlating the hinge-bending motion with the phospho-transfer mechanism.
authors.affiliation: Department of Biotechnology, Indian Institute of Technology, Kharagpur, India.
authors.forename: Amlan
authors.initials: A
authors.lastname: Roychowdhury
authors.forename: Anirban
authors.initials: A
authors.lastname: Kundu
authors.forename: Madhuparna
authors.initials: M
authors.lastname: Bose
authors.forename: Akanksha
authors.initials: A
authors.lastname: Gujar
authors.forename: Somnath
authors.initials: S
authors.lastname: Mukherjee
authors.forename: Amit Kumar
authors.initials: AK
authors.lastname: Das
mesh_terms: D002384:Catalysis; D020134:Catalytic Domain; D003198:Computer Simulation; D018360:Crystallography, X-Ray; D008024:Ligands; D008345:Manganese / Q000737:chemistry; D008958:Models, Molecular; D009038:Motion; D010736:Phosphoglycerate Mutase / Q000737:chemistry*; D011485:Protein Binding; D013211:Staphylococcus aureus / Q000201:enzymology*; D013379:Substrate Specificity; D013816:Thermodynamics; D014961:X-Ray Diffraction
chemical_list: D008024:Ligands; D008345:Manganese; D010736:Phosphoglycerate Mutase
keywords: Staphylococcus aureus; X-ray diffraction; catalytic mechanism; cofactor-independent phosphoglycerate mutase; hinge-bending motion