title: Structure of Leishmania major cysteine synthase.
abstract: Cysteine biosynthesis is a potential target for drug development against parasitic Leishmania species; these protozoa are responsible for a range of serious diseases. To improve understanding of this aspect of Leishmania biology, a crystallographic and biochemical study of L. major cysteine synthase has been undertaken, seeking to understand its structure, enzyme activity and modes of inhibition. Active enzyme was purified, assayed and crystallized in an orthorhombic form with a dimer in the asymmetric unit. Diffraction data extending to 1.8 Å resolution were measured and the structure was solved by molecular replacement. A fragment of γ-poly-D-glutamic acid, a constituent of the crystallization mixture, was bound in the enzyme active site. Although a D-glutamate tetrapeptide had insignificant inhibitory activity, the enzyme was competitively inhibited (K(i) = 4 µM) by DYVI, a peptide based on the C-terminus of the partner serine acetyltransferase with which the enzyme forms a complex. The structure surprisingly revealed that the cofactor pyridoxal phosphate had been lost during crystallization.
authors: Division of Biological Chemistry and Drug Discovery, College of Life Sciences, University of Dundee, Dundee DD1 5EH, Scotland.
authors: Paul K
authors: PK
authors: Fyfe
authors: Gareth D
authors: GD
authors: Westrop
authors: Tania
authors: T
authors: Ramos
authors: Sylke
authors: S
authors: Müller
authors: Graham H
authors: GH
authors: Coombs
authors: William N
authors: WN
authors: Hunter
mesh_terms: D003547:Cysteine Synthase / Q000037:antagonists & inhibitors / Q000737:chemistry* / Q000378:metabolism; D004791:Enzyme Inhibitors / Q000737:chemistry / Q000494:pharmacology; D018698:Glutamic Acid / Q000737:chemistry / Q000378:metabolism; D018320:Leishmania major / Q000201:enzymology*; D008958:Models, Molecular; D011485:Protein Binding; D054730:Protein Interaction Domains and Motifs; D020836:Protein Structure, Quaternary; D040681:Structural Homology, Protein
chemical_list: D004791:Enzyme Inhibitors; D018698:Glutamic Acid; D003547:Cysteine Synthase