title: Crystal structure and functional analysis of isocitrate lyases from Magnaporthe oryzae and Fusarium graminearum.
abstract: The glyoxylate cycle bypasses a CO2-generating step in the tricarboxylic acid (TCA) cycle and efficiently assimilates C2 compounds into intermediates that can be used in later steps of the TCA cycle. It plays an essential role in pathogen survival during host infection such that the enzymes involved in this cycle have been suggested as potential drug targets against human pathogens. Isocitrate lyase (ICL) catalyzes the first-step reaction of the glyoxylate cycle, using isocitrate from the TCA cycle as the substrate to produce succinate and glyoxylate. In this study we report the crystal structure of Magnaporthe oryzae ICL in both the ligand-free form and as a complex with Mg(2+), glyoxylate, and glycerol, as well as the structure of the Fusarium graminearum ICL complexed with Mn(2+) and malonate. We also describe the ligand-induced conformational changes in the catalytic loop and C-terminal region, both of which are essential for catalysis. Using various mutant ICLs in an activity assay, we gained insight into the function of residues within the active site. These structural and functional analyses provide detailed information with regard to fungal ICLs.
authors.affiliation: Department of Agricultural Biotechnology, Seoul National University, Seoul, Republic of Korea; Center for Fungal Pathogenesis, Seoul National University, Seoul, Republic of Korea.
authors.forename: Yangshin
authors.initials: Y
authors.lastname: Park
authors.affiliation: Department of Agricultural Biotechnology, Seoul National University, Seoul, Republic of Korea.
authors.forename: Yerim
authors.initials: Y
authors.lastname: Cho
authors.affiliation: Department of Agricultural Biotechnology, Seoul National University, Seoul, Republic of Korea; Center for Fungal Pathogenesis, Seoul National University, Seoul, Republic of Korea.
authors.forename: Yong-Hwan
authors.initials: YH
authors.lastname: Lee
authors.affiliation: Department of Agricultural Biotechnology, Seoul National University, Seoul, Republic of Korea; Center for Fungal Pathogenesis, Seoul National University, Seoul, Republic of Korea.
authors.forename: Yin-Won
authors.initials: YW
authors.lastname: Lee
authors.affiliation: Department of Agricultural Biotechnology, Seoul National University, Seoul, Republic of Korea; Center for Fungal Pathogenesis, Seoul National University, Seoul, Republic of Korea. Electronic address: srheesnu@snu.ac.kr.
authors.forename: Sangkee
authors.initials: S
authors.lastname: Rhee
mesh_terms: D020134:Catalytic Domain; D002952:Citric Acid Cycle; D018360:Crystallography, X-Ray; D005670:Fusarium / Q000201:enzymology*; D006038:Glyoxylates; D054884:Host-Pathogen Interactions; D007522:Isocitrate Lyase / Q000737:chemistry*; D008024:Ligands; D020082:Magnaporthe / Q000201:enzymology*; D011487:Protein Conformation
chemical_list: D006038:Glyoxylates; D008024:Ligands; D007522:Isocitrate Lyase; C031150:glyoxylic acid
keywords: Crystal structure; Enzyme assay; Glyoxylate cycle; Phytopathogen