Cloning of anArabidopsis thalianacDNA encoding cystathionine β-lyase by functional complementation inEscherichia coli

✍ Scribed by Stéphane Ravanel; Marie-Line Ruffet; Roland Douce

• Book ID: 104619123
• Publisher: Springer
• Year: 1995
• Tongue: English
• Weight: 705 KB
• Volume: 29
• Category: Article
• ISSN: 0167-4412
• DOI: 10.1007/bf00041177

✦ Synopsis

Cystathionine fl-lyase, the second enzyme involved in the methionine biosynthetic pathway in plants, catalyses the synthesis of homocysteine from cystathionine. A cDNA encoding cystathionine fl-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 50 372. A. thaliana cystathionine fl-lyase exhibits 22~o 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 fl-lyase is encoded by a single copy gene in A. thaliana.