Cloning and characterization of a cDNA coding a hydroxycinnamoyl-CoA quinate hydroxycinnamoyl transferase involved in chlorogenic acid biosynthesis in Lonicera japonica.

The flower buds of Lonicera japonica are widely used in Chinese medicine for their anti-inflammatory properties. The reason why L. japonica has potent and significant effects is that it contains various active components, especially chlorogenic acid (CGA). In the present study, we isolated a hydroxycinnamoyl-CoA quinate hydroxycinnamoyl transferase (HQT) gene encoding a protein of 439 amino acids from L. japonica. The RT-PCR results showed that tissue distribution of HQT was in accordance with the pattern of CGA content. The corresponding cDNAs were expressed in Escherichia coli as fusion proteins. Recombinant HQT exhibited catalysis activity in esterification of quinic acid with caffeoyl-CoA to generate CGA. Purified proteins demonstrated similar kinetic properties as HQT isolated from other species. This work is of significance for further studies concerned with strengthening the efficacy of L. japonica by means of improved CGA content and exploring the biosynthesis of CGA in vitro.