Abstract
Cystine lyases catalyze the breakdown of l-cystine to thiocysteine, pyruvate, and ammonia. Until now there are no reports of the identification of a plant cystine lyase at a molecular level, and it is not clear what biological role this class of enzymes have in plants. A cystine lyase was isolated from Brassica oleracea (L.), and partial amino acid sequencing allowed the corresponding full-length cDNA (BOCL3) to be cloned. The deduced amino acid sequence of BOCL3 showed highest homology to the deduced amino acid sequences of several Arabidopsis thaliana genes annotated as tyrosine aminotransferase-like, including a coronatine, jasmonic acid, and salt stress-inducible gene, CORI3 (78.8% identity), and the unidentified rooty/superroot1 gene (44.8% identity). A full-length expressed sequence tag clone of CORI3 was obtained and recombinant CORI3 was synthesized in Escherichia coli. Isolated recombinant CORI3 catalyzed a cystine lyase reaction, but no aminotransferase reactions. The present study identifies, for the first time, a cystine lyase from plants at a molecular level and redefines the functional assignment of the only functionally identified member of a group of A. thaliana genes annotated as tyrosine aminotransferase-like.
Highlights
Cystine lyases catalyze the breakdown of L-cystine to thiocysteine, pyruvate, and ammonia
The present study identifies, for the first time, a cystine lyase from plants at a molecular level and redefines the functional assignment of the only functionally identified member of a group of A. thaliana genes annotated as tyrosine aminotransferase-like
This paper describes the redefinition of CORI3, incorrectly annotated as a tyrosine aminotransferase in the Arabidopsis thaliana genome, as the first identified plant cystine lyase
Summary
Cystine lyases catalyze the breakdown of L-cystine to thiocysteine, pyruvate, and ammonia. The present study identifies, for the first time, a cystine lyase from plants at a molecular level and redefines the functional assignment of the only functionally identified member of a group of A. thaliana genes annotated as tyrosine aminotransferase-like. Aminotransferases (EC 2.6.1.-) are similar to most CS-lyases in that they utilize PLP as a co-factor and that they are involved in amino acid metabolism [7]. This paper describes the redefinition of CORI3, incorrectly annotated as a tyrosine aminotransferase in the Arabidopsis thaliana genome, as the first identified plant cystine lyase. CORI3, a coronatine, jasmonic acid [10] and salt stress-inducible [11] A. thaliana transcript that encodes for a protein with tyrosine aminotransferase activity was reported last year [12]. The identification of a new stress- and plant “signal”-inducible member of the CS-lyase family at the molecular level adds new impetus for an examination of the role of CS-lyases in such diverse areas as primary sulfur metabolism, hormone metabolism [14], and secondary plant metabolism [2]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
