RRC ID 49562
Author Nakajima K, Hashimoto T, Yamada Y.
Title Two tropinone reductases with different stereospecificities are short-chain dehydrogenases evolved from a common ancestor.
Journal Proc. Natl. Acad. Sci. U.S.A.
Abstract In the biosynthetic pathway of tropane alkaloids, tropinone reductase (EC 1.1.1.236) (TR)-I and TR-II, respectively, reduce a common substrate, tropinone, stereospecifically to the stereoisomeric alkamines tropine and pseudotropine (psi-tropine). cDNA clones coding for TR-I and TR-II, as well as a structurally related cDNA clone with an unknown function, were isolated from the solanaceous plant Datura stramonium. The cDNA clones for TR-I and TR-II encode polypeptides containing 273 and 260 amino acids, respectively, and when these clones were expressed in Escherichia coli, the recombinant TRs showed the same strict stereospecificity as that observed for the native TRs that had been isolated from plants. The deduced amino acid sequences of the two clones showed an overall identity of 64% in 260-amino acid residues and also shared significant similarities with enzymes in the short-chain, nonmetal dehydrogenase family. Genomic DNA-blot analysis detected the TR-encoding genes in three tropane alkaloid-producing solanaceous species but did not detect them in tobacco. We discuss how the two TRs may have evolved to catalyze the opposite stereospecific reductions.
Volume 90(20)
Pages 9591-5
Published 1993-10-15
PMID 8415746
PMC PMC47615
MeSH Alcohol Oxidoreductases / genetics* Alcohol Oxidoreductases / metabolism Amino Acid Sequence Base Sequence Biological Evolution Cloning, Molecular DNA, Complementary / genetics Genes, Plant Molecular Sequence Data Oligodeoxyribonucleotides / chemistry Sequence Alignment Sequence Homology, Amino Acid Stereoisomerism Substrate Specificity Tropanes / chemistry*
IF 9.504
Resource
DNA material pDTR 1 (RDB01548) pDTR 2 (RDB01549).