Cloning of an Arabidopsis thaliana cDNA encoding cystathionine beta-lyase by functional complementation in Escherichia coli.
Cystathionine beta-lyase, the second enzyme involved in the methionine biosynthetic pathway in plants, catalyses the synthesis of homocysteine from cystathionine. A cDNA encoding cystathionine beta-lyase was cloned from an Arabidopsis thaliana expression library by complementation of an Escherichia coli mutant deficient in this enzyme. As deduced from the full-length nucleotide sequence (1.7 kb), the polypeptide contains 464 amino acids and presents a predicted M(r) of 50372. A. thaliana cystathionine beta-lyase exhibits 22% sequence identity with the E. coli corresponding enzyme and contains a 70 amino acid N-terminal additional sequence compared with the bacterial protein. Since the general features of chloroplast transit peptides could be observed in this amino-terminal extension, we propose a chloroplast localization for the cDNA-encoded enzyme. Southern blot analysis suggested that cystathionine beta-lyase is encoded by a single copy gene in A. thaliana.
Laboratoire Mixte CNRS/Rhône-Poulenc (UM41 associée au Centre National de la Recherche Scientifique), Rhône-Poulenc Agrochimie, Lyon, France.
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D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000201:enzymology / Q000235:genetics*; D001483:Base Sequence; D002736:Chloroplasts / Q000201:enzymology; D003001:Cloning, Molecular; D018076:DNA, Complementary / Q000235:genetics; D004926:Escherichia coli / Q000235:genetics; D005816:Genetic Complementation Test; D008190:Lyases / Q000235:genetics*; D008715:Methionine / Q000096:biosynthesis; D008969:Molecular Sequence Data; D021382:Protein Sorting Signals / Q000235:genetics; D017422:Sequence Analysis, DNA; D017386:Sequence Homology, Amino Acid
D018076:DNA, Complementary; D021382:Protein Sorting Signals; D008715:Methionine; D008190:Lyases; C019965:cystathionine beta-lyase