(+)-Pinoresinol/(-)-lariciresinol reductase from Linum perenne Himmelszelt involved in the biosynthesis of justicidin B

A cDNA encoding a pinoresinol-lariciresinol reductase PLR (PLR-Lpl) was isolated from a cell culture of Linum perenne Himmelszelt accumulating the arylnaphthalene lignan justicidin B. The recombinant PLR-Lpl prefers (+)-pinoresinol in the first reaction step, but (-)-lariciresinol in the second step. Therefore, it is the first PLR described with opposite enantiospecificity within the two reaction steps catalysed by PLRs. Hairy root lines transformed with an ihpRNAi construct to suppress ph- gene expression show less mRNA accumulation for the ph-Lp] gene and PLR enzyme activity. Justicidin B accumulation was reduced down to 24% in comparison to control lines showing the involvement of PLR-LpI in the biosynthesis of justicidin B. (c) 2007 Federation of European Biochemical Societies. Published by Elsevier B.V. All rights reserved.