Structure of 1-aminocyclopropane-1-carboxylate synthase, a key enzyme in the biosynthesis of the plant hormone ethylene.

The 2.4 A crystal structure of the vitamin B6-dependent enzyme 1-aminocyclopropane-1-carboxylate (ACC) synthase is described. This enzyme catalyses the committed step in the biosynthesis of ethylene, a plant hormone that is responsible for the initiation of fruit ripening and for regulating many other developmental processes. ACC synthase has 15 % sequence identity with the well-studied aspartate aminotransferase, and a completely different catalytic activity yet the overall folds and the active sites are very similar. The new structure together with available biochemical data enables a comparative mechanistic analysis that largely explains the catalytic roles of the conserved and non-conserved active site residues. An external aldimine reaction intermediate (external aldimine with ACC, i.e. with the product) has been modeled. The new structure provides a basis for the rational design of inhibitors with broad agricultural applications.

[1]  G. Eichele,et al.  Three-dimensional structure of a pyridoxal-phosphate-dependent enzyme, mitochondrial aspartate aminotransferase. , 1980, Proceedings of the National Academy of Sciences of the United States of America.

[2]  B. Shen,et al.  Crystal structure of human recombinant ornithine aminotransferase. , 1998, Journal of molecular biology.

[3]  J. S. Lee,et al.  Random mutagenesis of 1-aminocyclopropane-1-carboxylate synthase: a key enzyme in ethylene biosynthesis. , 1998, Proceedings of the National Academy of Sciences of the United States of America.

[4]  P. Oeller,et al.  Reversible inhibition of tomato fruit senescence by antisense RNA. , 1991, Science.

[5]  P. Kraulis.  A program to produce both detailed and schematic plots of protein structures , 1991 .

[6]  D. Metzler,et al.  Refinement and Comparisons of the Crystal Structures of Pig Cytosolic Aspartate Aminotransferase and Its Complex with 2-Methylaspartate* , 1997, The Journal of Biological Chemistry.

[7]  Rolf Apweiler,et al.  The SWISS-PROT protein sequence database and its supplement TrEMBL in 2000 , 2000, Nucleic Acids Res..

[8]  J. Jansonius,et al.  Structure, evolution and action of vitamin B6-dependent enzymes. , 1998, Current opinion in structural biology.

[9]  Rolf Apweiler,et al.  The SWISS-PROT protein sequence data bank and its supplement TrEMBL , 1997, Nucleic Acids Res..

[10]  C. Mcphalen,et al.  X-ray structure refinement and comparison of three forms of mitochondrial aspartate aminotransferase. , 1993, Journal of molecular biology.

[11]  G. Bufler.  ETHYLENE BIOSYNTHESIS AND ACTION , 1986 .

[12]  P. Christen,et al.  Aminotransferases: demonstration of homology and division into evolutionary subgroups. , 1993, European journal of biochemistry.

[13]  N. Hoffman,et al.  Ethylene biosynthesis and its regulation in higher plants , 1984 .

[14]  M. F. White,et al.  Expression of apple 1-aminocyclopropane-1-carboxylate synthase in Escherichia coli: kinetic characterization of wild-type and active-site mutant forms. , 1994, Proceedings of the National Academy of Sciences of the United States of America.

[15]  J. Kirsch,et al.  Kinetic and spectroscopic investigations of wild-type and mutant forms of apple 1-aminocyclopropane-1-carboxylate synthase. , 1997, Biochemistry.

[16]  A. Bleecker,et al.  Stereochemical course of the reaction catalyzed by the pyridoxal phosphate-dependent enzyme 1-aminocyclopropane-1-carboxylate synthase. , 1985, Proceedings of the National Academy of Sciences of the United States of America.

[17]  Shangfa Yang,et al.  A Novel Bifunctional Fusion Enzyme Catalyzing Ethylene Synthesis via 1-Aminocyclopropane1-carboxylic Acid* , 1996, The Journal of Biological Chemistry.

[18]  Shangfa Yang,et al.  1-Aminocyclopropanecarboxylate synthase, a key enzyme in ethylene biosynthesis. , 1979, Archives of biochemistry and biophysics.

[19]  J. Kirsch,et al.  The reaction catalyzed by Escherichia coli aspartate aminotransferase has multiple partially rate-determining steps, while that catalyzed by the Y225F mutant is dominated by ketimine hydrolysis. , 1996, Biochemistry.

[20]  C. Sander,et al.  Protein structure comparison by alignment of distance matrices. , 1993, Journal of molecular biology.

[21]  R. Huber,et al.  Accurate Bond and Angle Parameters for X-ray Protein Structure Refinement , 1991 .

[22]  Joël Janin,et al.  Specific versus non-specific contacts in protein crystals , 1997, Nature Structural Biology.

[23]  M. Sanner,et al.  Reduced surface: an efficient way to compute molecular surfaces. , 1996, Biopolymers.

[24]  P. Christen,et al.  Evolutionary relationships among pyridoxal‐5′‐phosphate‐dependent enzymes , 1994 .

[25]  M. Hennig,et al.  Crystal structure of glutamate-1-semialdehyde aminomutase: an alpha2-dimeric vitamin B6-dependent enzyme with asymmetry in structure and active site reactivity. , 1997, Proceedings of the National Academy of Sciences of the United States of America.

[26]  G J Barton,et al.  ALSCRIPT: a tool to format multiple sequence alignments. , 1993, Protein engineering.

[27]  G. Eichele,et al.  Mechanism of action of aspartate aminotransferase proposed on the basis of its spatial structure. , 1984, Journal of molecular biology.

[28]  H. Hayashi,et al.  The imine-pyridine torsion of the pyridoxal 5'-phosphate Schiff base of aspartate aminotransferase lowers its pKa in the unliganded enzyme and is crucial for the successive increase in the pKa during catalysis. , 1998, Biochemistry.

[29]  S. Colowick,et al.  Methods in Enzymology , Vol , 1966 .

[30]  B. Shen,et al.  Human ornithine aminotransferase complexed with L-canaline and gabaculine: structural basis for substrate recognition. , 1997, Structure.

[31]  Ann M Stock,et al.  Crystal structure of the chemotaxis receptor methyltransferase CheR suggests a conserved structural motif for binding S-adenosylmethionine. , 1997, Structure.

[32]  J. Kirsch,et al.  The tyrosine-225 to phenylalanine mutation of Escherichia coli aspartate aminotransferase results in an alkaline transition in the spectrophotometric and kinetic pKa values and reduced values of both kcat and Km. , 1991, Biochemistry.

[33]  Geoffrey J. Barton,et al.  Protein sequence alignments: a strategy for the hierarchical analysis of residue conservation , 1993, Comput. Appl. Biosci..

[34]  R. Huber,et al.  Crystal structure of the pyridoxal-5'-phosphate dependent cystathionine beta-lyase from Escherichia coli at 1.83 A. , 1996, Journal of molecular biology.

[35]  A. Theologis,et al.  One rotten apple spoils the whole bushel: The role of ethylene in fruit ripening , 1992, Cell.

[36]  G. Capitani,et al.  Crystal structure of human ornithine aminotransferase complexed with the highly specific and potent inhibitor 5-fluoromethylornithine. , 1999, Journal of molecular biology.

[37]  E A Merritt,et al.  Raster3D: photorealistic molecular graphics. , 1997, Methods in enzymology.

[38]  J. Zou,et al.  Improved methods for building protein models in electron density maps and the location of errors in these models. , 1991, Acta crystallographica. Section A, Foundations of crystallography.

[39]  G. Bricogne,et al.  [27] Maximum-likelihood heavy-atom parameter refinement for multiple isomorphous replacement and multiwavelength anomalous diffraction methods. , 1997, Methods in enzymology.

[40]  J. Thornton,et al.  PROMOTIF—A program to identify and analyze structural motifs in proteins , 1996, Protein science : a publication of the Protein Society.

[41]  A. Theologis,et al.  Two genes encoding 1-aminocyclopropane-1-carboxylate synthase in zucchini (Cucurbita pepo) are clustered and similar but differentially regulated. , 1991, Proceedings of the National Academy of Sciences of the United States of America.

[42]  M. F. White,et al.  Crystallization and preliminary X-ray analysis of recombinant 1-aminocyclopropane-1-carboxylate synthase from apple. A key enzyme in the biosynthesis of the plant hormone ethylene. , 1994, Journal of molecular biology.

[43]  C. Sander,et al.  Errors in protein structures , 1996, Nature.

[44]  P. Christen,et al.  The covalent structure of mitochondrial aspartate aminotransferase from chicken. Identification of segments of the polypeptide chain invariant specifically in the mitochondrial isoenzyme. , 1983, The Journal of biological chemistry.

[45]  Collaborative Computational,et al.  The CCP4 suite: programs for protein crystallography. , 1994, Acta crystallographica. Section D, Biological crystallography.

[46]  P. K. Mehta,et al.  Homology of 1-aminocyclopropane-1-carboxylate synthase, 8-amino-7-oxononanoate synthase, 2-amino-6-caprolactam racemase, 2,2-dialkylglycine decarboxylase, glutamate-1-semialdehyde 2,1-aminomutase and isopenicillin-N-epimerase with aminotransferases. , 1994, Biochemical and biophysical research communications.

[47]  A M Lesk,et al.  Domain closure in mitochondrial aspartate aminotransferase. , 1992, Journal of molecular biology.