β-Cyanoalanine synthase and cysteine synthase from potato: Molecular cloning, biochemical characterization, and spatial and hormonal regulation

Akiko Maruyama, Kazuki Saito, Kimiharu Ishizawa

Research output: Contribution to journalArticlepeer-review

56 Citations (Scopus)

Abstract

β-Cyanoalanine synthase (CAS, L-3-cyanoalanine synthase; EC 4.4.1.9) is the most important enzyme in cyanide metabolism. In addition to CAS, cysteine synthase (CS, EC 4.2.99.8) possesses CAS activity. To explore the physiological significance of cyanide metabolism, we isolated the cDNA clones corresponding to purified CAS (designated PCAS-1 and PCAS-2) and CS (designated PCS-1 and PCS-2) from potato using the information of these amino acid sequences. The recombinant proteins of PCS-1, PCS-2 and PCAS-1 catalyzed both CAS and CS reactions, although the ratios between CAS and CS activity were remarkably different. PCAS-1 preferred the substrates for the CAS reaction to the substrates for the CS reaction. From the kinetic characters and homology of amino acid sequences with known CS-like proteins, PCS-1, PCS-2 and PCAS-1 were identified as cytosolic CS, plastidic CS and mitochondrial CAS, respectively. The highest level of CAS activity, CAS protein and its mRNA were detected in potato buds. Stimulation of CAS activity and protein accumulation by ethylene without the concomitant increase of its mRNA suggested that ethylene induces CAS protein accumulation at the post-transcriptional level.

Original languageEnglish
Pages (from-to)749-760
Number of pages12
JournalPlant Molecular Biology
Volume46
Issue number6
DOIs
Publication statusPublished - Oct 9 2001
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Agronomy and Crop Science
  • Genetics
  • Plant Science

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