title: Kinetic mechanism and order of substrate binding for sn-glycerol-3-phosphate acyltransferase from squash (Cucurbita moschata).
abstract: sn-Glycerol-3-phosphate acyltransferase (G3PAT, EC 2.3.1.15), a component of glycerolipid biosynthesis, is an important enzyme in chilling sensitivity in plants. The three-dimensional structure of the enzyme from squash (Cucurbita moschata), without bound substrate, has been determined [Turnbull et al. (2001) Acta Crystallogr. D 57, 451-453; Turnbull et al. (2001) Structure 9, 347-353]. Here we report the kinetic mechanism of plastidial G3PAT from squash and the order of substrate binding using acyl-acyl carrier protein (acyl-ACP) substrates. The reaction proceeds via a compulsory-ordered ternary complex with acyl-ACP binding before glycerol-3-phosphate. We have also determined that the reaction will proceed with C(4:0)-CoA, C(6:0)-CoA and C(12:0)-ACP substrates, allowing a wider choice of acyl groups for future co-crystallisation studies.
authors.affiliation: The University of Durham, Department of Biological Sciences, Science Laboratories, South Road, Durham DH1 3LE, UK.
authors.forename: Matthew W
authors.initials: MW
authors.lastname: Hayman
authors.forename: Tony
authors.initials: T
authors.lastname: Fawcett
authors.forename: Antoni R
authors.initials: AR
authors.lastname: Slabas
mesh_terms: D000213:Acyl Carrier Protein / Q000737:chemistry; D001667:Binding, Competitive / Q000502:physiology; D028464:Cucurbita / Q000201:enzymology*; D005227:Fatty Acids / Q000737:chemistry; D005992:Glycerol-3-Phosphate O-Acyltransferase / Q000737:chemistry*; D005994:Glycerophosphates / Q000737:chemistry; D007700:Kinetics; D046911:Macromolecular Substances; D010940:Plant Proteins / Q000737:chemistry; D018087:Plastids / Q000201:enzymology; D011485:Protein Binding / Q000502:physiology; D013379:Substrate Specificity / Q000502:physiology
chemical_list: D000213:Acyl Carrier Protein; D005227:Fatty Acids; D005994:Glycerophosphates; D046911:Macromolecular Substances; D010940:Plant Proteins; C029620:alpha-glycerophosphoric acid; D005992:Glycerol-3-Phosphate O-Acyltransferase