title: Crystallographic substrate binding studies of Leishmania mexicana SCP2-thiolase (type-2): unique features of oxyanion hole-1.
abstract: Structures of the C123A variant of the dimeric Leishmania mexicana SCP2-thiolase (type-2) (Lm-thiolase), complexed with acetyl-CoA and acetoacetyl-CoA, respectively, are reported. The catalytic site of thiolase contains two oxyanion holes, OAH1 and OAH2, which are important for catalysis. The two structures reveal for the first time the hydrogen bond interactions of the CoA-thioester oxygen atom of the substrate with the hydrogen bond donors of OAH1 of a CHH-thiolase. The amino acid sequence fingerprints ( xS, EAF, G P) of three catalytic loops identify the active site geometry of the well-studied CNH-thiolases, whereas SCP2-thiolases (type-1, type-2) are classified as CHH-thiolases, having as corresponding fingerprints xS, DCF and G P. In all thiolases, OAH2 is formed by the main chain NH groups of two catalytic loops. In the well-studied CNH-thiolases, OAH1 is formed by a water (of the Wat-Asn(NEAF) dyad) and NE2 (of the GHP-histidine). In the two described liganded Lm-thiolase structures, it is seen that in this CHH-thiolase, OAH1 is formed by NE2 of His338 (HDCF) and His388 (GHP). Analysis of the OAH1 hydrogen bond networks suggests that the GHP-histidine is doubly protonated and positively charged in these complexes, whereas the HDCF histidine is neutral and singly protonated.
authors.affiliation: Faculty of Biochemistry and Molecular Medicine, Biocenter Oulu, University of Oulu, FIN-90014, Finland.|Present address: Department of Biochemistry, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, NY 10461, USA.
authors.forename: Rajesh K
authors.initials: RK
authors.lastname: Harijan
authors.affiliation: Faculty of Biochemistry and Molecular Medicine, Biocenter Oulu, University of Oulu, FIN-90014, Finland.
authors.forename: Tiila-Riikka
authors.initials: TR
authors.lastname: Kiema
authors.affiliation: Faculty of Biochemistry and Molecular Medicine, Biocenter Oulu, University of Oulu, FIN-90014, Finland.
authors.forename: Shahan M
authors.initials: SM
authors.lastname: Syed
authors.affiliation: Faculty of Biochemistry and Molecular Medicine, Biocenter Oulu, University of Oulu, FIN-90014, Finland.
authors.forename: Imran
authors.initials: I
authors.lastname: Qadir
authors.affiliation: Centre de Résonance Magnétique des Systèmes Biologiques (RMSB), UMR5536, Université de Bordeaux, CNRS, 146 rue Léo Saignat, 33076 Bordeaux, France.|Present address: Laboratoire de Microbiologie Fondamentale et Pathogénicité (MFP), UMR5234, Université de Bordeaux, CNRS, 146 rue Léo Saignat, 33076 Bordeaux, France.
authors.forename: Muriel
authors.initials: M
authors.lastname: Mazet
authors.affiliation: Centre de Résonance Magnétique des Systèmes Biologiques (RMSB), UMR5536, Université de Bordeaux, CNRS, 146 rue Léo Saignat, 33076 Bordeaux, France.|Present address: Laboratoire de Microbiologie Fondamentale et Pathogénicité (MFP), UMR5234, Université de Bordeaux, CNRS, 146 rue Léo Saignat, 33076 Bordeaux, France.
authors.forename: Frédéric
authors.initials: F
authors.lastname: Bringaud
authors.affiliation: Centre for Immunity, Infection and Evolution and Centre for Translational and Chemical Biology, School of Biological Sciences, The King's Buildings, The University of Edinburgh, Charlotte Auerbach Road, Edinburgh EH9 3FL, UK.
authors.forename: Paul A M
authors.initials: PAM
authors.lastname: Michels
authors.affiliation: Faculty of Biochemistry and Molecular Medicine, Biocenter Oulu, University of Oulu, FIN-90014, Finland.
authors.forename: Rik K
authors.initials: RK
authors.lastname: Wierenga
mesh_terms: D000101:Acetyl-CoA C-Acetyltransferase / Q000737:chemistry*; D020134:Catalytic Domain; D018360:Crystallography, X-Ray; D007894:Leishmania mexicana / Q000201:enzymology*; D017433:Protein Structure, Secondary; D015800:Protozoan Proteins / Q000737:chemistry*
chemical_list: D015800:Protozoan Proteins; D000101:Acetyl-CoA C-Acetyltransferase
keywords: Coenzyme A; Leishmania mexicana; SCP2-thiolase; Trypanosoma brucei; crystal structure; leishmaniasis; ligand binding; lipid metabolism; sleeping sickness; β-oxidation