An Elicitor-Inducible NADP-Malic Enzyme in Lithospermum erythrorhizon Cultured Cells : cDNA Cloning and Characterization

The differential display technique was used to isolate genes expressed during yeast extract-induced rosmarinic acid biosynthesis in Lithospermum erythrorhizon cell suspension cultures, and a cDNA clone whose deduced amino acid sequence is similar to plant cytosolic NADP-malic enzymes was identified and designated LeME. The heterologously-expressed LeME oxidized L-malate in presence of NADP, but it did not catalyze formation of 4-hydroxyphenyllactic acid from 4-hydroxyphenylpyruvate in presence of NADPH, one of the crucial biosynthetic steps leading to rosmarinic acid. The potential role of LeME in elicitor-inducible rosmarinic acid biosynthesis is discussed.