Abstract
Previously, we identified 3, 8-divinyl protochlorophyllide a 8-vinyl reductase (DVR) gene from Arabidopsis.
DVR reduces an 8-vinyl group on chlorophyll to an ethyl group. The substrate of DVR is assumed to be DVPchlide a, and chlorophyll biosynthesis pathway was constructed based on this assumption. However, real substrate of DVR is not determined because the enzymatic experiment has not been done with purified enzymes or recombinant proteins.
In order to determine the chlorophyll biosynthesis pathway, we carried out enzymatic experiments using the recombinant DVR protein and chlorophyll intermediate molecules. These experiments showed DVR had high activity with DVChlide a, but low or no activity with other pigments. We also investigated the flow of chlorophyll intermediates in Arabidopsis. Conversion of DVPchlide a to MVPchlide a required several hours but DVChlide a was reduced within a few seconds.
On the basis of these experiments, we will propose revised chlorophyll biosynthesis pathway.
