Characterization, and expression profile of a phenylalanine ammonia lyase gene from Jatropha curcas L.

A PAL gene designated as JcPAL1 was cloned from J. curcas L. The full-length is 2336 bp in size with one intron and two exons, encoding a polypeptide of 713 amino acids. Its 5'-upstream region is rich in putative cis-elements including not only PAL typical TATA box, L-box and transcriptional initiation site (TIS) but also light responding motifs. Expression pattern analysis indicated that JcPAL1 were expressed in all tissues, most highly in flowers. When Treated with ABA, GA3, high and low temperature, expression of JcPAL1 were induced. Recombinant JcPAL1 has a pH optimum at 8.7 and a temperature optimum at 60°C in 100 mM Tris-HCl buffer. The Km and Kcat values are 0.125 mM and 1.73 S(-1) for L: -phenylalanine, and 1.312 mM and 0.109 S(-1) for L: -tyrosine, respectively. These findings suggested that JcPAL1 might involve in the J. curcas responding to various stresses and L: -Phe should be its true physiological substrate. This study is essential prior to uncover whether and how the PAL initiated phenylpropanoid metabolic networks functioning in the defense responses of J. curcas.