title: Oxaloacetate hydrolase, the C-C bond lyase of oxalate secreting fungi.
abstract: Oxalate secretion by fungi is known to be associated with fungal pathogenesis. In addition, oxalate toxicity is a concern for the commercial application of fungi in the food and drug industries. Although oxalate is generated through several different biochemical pathways, oxaloacetate acetylhydrolase (OAH)-catalyzed hydrolytic cleavage of oxaloacetate appears to be an especially important route. Below, we report the cloning of the Botrytis cinerea oahA gene and the demonstration that the disruption of this gene results in the loss of oxalate formation. In addition, through complementation we have shown that the intact B. cinerea oahA gene restores oxalate production in an Aspergillus niger mutant strain, lacking a functional oahA gene. These observations clearly indicate that oxalate production in A. niger and B. cinerea is solely dependent on the hydrolytic cleavage of oxaloacetate catalyzed by OAH. In addition, the B. cinera oahA gene was overexpressed in Escherichia coli and the purified OAH was used to define catalytic efficiency, substrate specificity, and metal ion activation. These results are reported along with the discovery of the mechanism-based, tight binding OAH inhibitor 3,3-difluorooxaloacetate (K(i) = 68 nM). Finally, we propose that cellular uptake of this inhibitor could reduce oxalate production.
authors.affiliation: Department of Chemistry, University of New Mexico, Albuquerque, New Mexico 87131.
authors.forename: Ying
authors.initials: Y
authors.lastname: Han
authors.affiliation: Laboratory of Microbiology Section Fungal Genomics, Wageningen University, Dreijenlaan 2, 6703 HA Wageningen, The Netherlands.
authors.forename: Henk-Jan
authors.initials: HJ
authors.lastname: Joosten
authors.affiliation: Department of Chemistry, University of New Mexico, Albuquerque, New Mexico 87131.
authors.forename: Weiling
authors.initials: W
authors.lastname: Niu
authors.affiliation: Department of Chemistry, University of New Mexico, Albuquerque, New Mexico 87131.
authors.forename: Zhiming
authors.initials: Z
authors.lastname: Zhao
authors.affiliation: Department of Chemistry, University of New Mexico, Albuquerque, New Mexico 87131.
authors.forename: Patrick S
authors.initials: PS
authors.lastname: Mariano
authors.affiliation: Laboratory of Phytopathology, Wageningen University, Binnenhaven 5, 6709 PD Wageningen, The Netherlands.
authors.forename: Melisa
authors.initials: M
authors.lastname: McCalman
authors.affiliation: Laboratory of Phytopathology, Wageningen University, Binnenhaven 5, 6709 PD Wageningen, The Netherlands.
authors.forename: Jan
authors.initials: J
authors.lastname: van Kan
authors.affiliation: Laboratory of Microbiology Section Fungal Genomics, Wageningen University, Dreijenlaan 2, 6703 HA Wageningen, The Netherlands. Electronic address: peter.schaap@wur.nl.
authors.forename: Peter J
authors.initials: PJ
authors.lastname: Schaap
authors.affiliation: Department of Chemistry, University of New Mexico, Albuquerque, New Mexico 87131. Electronic address: dd39@unm.edu.
authors.forename: Debra
authors.initials: D
authors.lastname: Dunaway-Mariano
mesh_terms: D001234:Aspergillus niger / Q000201:enzymology / Q000235:genetics; D020171:Botrytis / Q000201:enzymology* / Q000235:genetics; D005656:Fungal Proteins / Q000737:chemistry / Q000235:genetics / Q000502:physiology; D006867:Hydrolases / Q000737:chemistry / Q000235:genetics / Q000502:physiology*; D008969:Molecular Sequence Data; D010070:Oxalates / Q000378:metabolism*
chemical_list: D005656:Fungal Proteins; D010070:Oxalates; D006867:Hydrolases; C054172:oxaloacetase