Open AccessMolecular characterization of two plant flavonol sulfotransferases.
Author(s) -
Luc Varin,
Vincenzo Deluca,
Ragai K. Ibrahim,
Normand Brisson
Publication year - 1992
Publication title -
proceedings of the national academy of sciences of the united states of america
Language(s) - English
Resource type - Journals
eISSN - 1091-6490
pISSN - 0027-8424
DOI - 10.1073/pnas.89.4.1286
Subject(s) - complementary dna , biology , peptide sequence , amino acid , biochemistry , escherichia coli , microbiology and biotechnology , cdna library , open reading frame , fusion protein , nucleic acid sequence , coding region , dna , gene , recombinant dna
cDNA clones coding for flavonol 3- and 4'-sulfotransferases (STs) were isolated by antibody screening of a cDNA expression library produced from poly(A)+ RNA extracted from terminal buds of Flaveria chloraefolia. Sequence analysis revealed full-length cDNA clones with open reading frames of 933 and 960 base pairs, which encode polypeptides containing 311 and 320 amino acids, respectively. This corresponds to a molecular mass of 36,442 Da for the 3-ST and 37,212 Da for the 4'-ST. Expression of these clones in Escherichia coli led to the synthesis of beta-galactosidase-ST fusion proteins having the same substrate and position specificities as those for the 3- and 4'-flavonol ST enzymes isolated from the plant. Comparison of the deduced amino acid sequence of the two clones revealed an overall identity of 69% in 311 amino acid residues. The two flavonol STs of F. chloraefolia also shared significant sequence similarities with steroid and aryl STs found in animal tissues and with the senescence marker protein 2 isolated from rat liver, suggesting an evolutionary link between plant and animal STs.