title: Structure and mechanism of soybean ATP sulfurylase and the committed step in plant sulfur assimilation.
abstract: Enzymes of the sulfur assimilation pathway are potential targets for improving nutrient content and environmental stress responses in plants. The committed step in this pathway is catalyzed by ATP sulfurylase, which synthesizes adenosine 5'-phosphosulfate (APS) from sulfate and ATP. To better understand the molecular basis of this energetically unfavorable reaction, the x-ray crystal structure of ATP sulfurylase isoform 1 from soybean (Glycine max ATP sulfurylase) in complex with APS was determined. This structure revealed several highly conserved substrate-binding motifs in the active site and a distinct dimerization interface compared with other ATP sulfurylases but was similar to mammalian 3'-phosphoadenosine 5'-phosphosulfate synthetase. Steady-state kinetic analysis of 20 G. max ATP sulfurylase point mutants suggests a reaction mechanism in which nucleophilic attack by sulfate on the α-phosphate of ATP involves transition state stabilization by Arg-248, Asn-249, His-255, and Arg-349. The structure and kinetic analysis suggest that ATP sulfurylase overcomes the energetic barrier of APS synthesis by distorting nucleotide structure and identifies critical residues for catalysis. Mutations that alter sulfate assimilation in Arabidopsis were mapped to the structure, which provides a molecular basis for understanding their effects on the sulfur assimilation pathway.
authors.affiliation: Department of Biology, Washington University, St. Louis, Missouri 63130.
authors.forename: Jonathan
authors.initials: J
authors.lastname: Herrmann
authors.affiliation: Department of Biology, Washington University, St. Louis, Missouri 63130.
authors.forename: Geoffrey E
authors.initials: GE
authors.lastname: Ravilious
authors.affiliation: Department of Biology, Washington University, St. Louis, Missouri 63130.
authors.forename: Samuel E
authors.initials: SE
authors.lastname: McKinney
authors.affiliation: Department of Biology, Washington University, St. Louis, Missouri 63130.
authors.forename: Corey S
authors.initials: CS
authors.lastname: Westfall
authors.affiliation: Department of Biology, Washington University, St. Louis, Missouri 63130.
authors.forename: Soon Goo
authors.initials: SG
authors.lastname: Lee
authors.affiliation: John Innes Centre, Norwich Research Park, Norwich NR4 7UH, United Kingdom.
authors.forename: Patrycja
authors.initials: P
authors.lastname: Baraniecka
authors.affiliation: John Innes Centre, Norwich Research Park, Norwich NR4 7UH, United Kingdom; Department of Life Sciences and Systems Biology, University of Torino, Viale Mattioli 25, I-10125 Torino, Italy.
authors.forename: Marco
authors.initials: M
authors.lastname: Giovannetti
authors.affiliation: John Innes Centre, Norwich Research Park, Norwich NR4 7UH, United Kingdom.
authors.forename: Stanislav
authors.initials: S
authors.lastname: Kopriva
authors.affiliation: Plant Genetics Research Unit, United States Department of Agriculture-Agricultural Research Service, University of Missouri, Columbia, Missouri 65211.
authors.forename: Hari B
authors.initials: HB
authors.lastname: Krishnan
authors.affiliation: Department of Biology, Washington University, St. Louis, Missouri 63130. Electronic address: jjez@biology2.wustl.edu.
authors.forename: Joseph M
authors.initials: JM
authors.lastname: Jez
mesh_terms: D000250:Adenosine Phosphosulfate / Q000737:chemistry*; D000255:Adenosine Triphosphate / Q000737:chemistry; D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000378:metabolism; D002384:Catalysis; D020134:Catalytic Domain; D018360:Crystallography, X-Ray; D006239:Haplotypes; D006860:Hydrogen Bonding; D007700:Kinetics; D062105:Molecular Docking Simulation; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D009154:Mutation; D017434:Protein Structure, Tertiary; D017386:Sequence Homology, Amino Acid; D013025:Glycine max / Q000201:enzymology*; D013379:Substrate Specificity; D013430:Sulfate Adenylyltransferase / Q000737:chemistry*; D013455:Sulfur / Q000737:chemistry*
chemical_list: D000250:Adenosine Phosphosulfate; D013455:Sulfur; D000255:Adenosine Triphosphate; D013430:Sulfate Adenylyltransferase
keywords: Enzyme Mechanisms; Enzyme Structure; Plant; Plant Biochemistry; Protein Structure