Molecular characterization and expression analysis on two isogenes encoding 3-deoxy-D-arabino-heptulosonate 7-phosphate synthase in grapes.

3-Deoxy-D-arabino-heptulosonate 7-phosphate synthase (DAHPS) is an entry enzyme of the shikimate pathway that connects primary carbohydrate metabolism with the biosynthesis of most secondary metabolites in plants. In the present study, two DAHPS cDNAs were cloned from grape berries (Vitis vinifera) and designated as VvDAHPS-1 and VvDAHPS-2. These two cDNA sequences share 75.7% of the identities. Their DNA corresponding to the two isogenes both contain four introns. The deduced proteins from two cDNAs had different NH(4)-terminal regions and putative mature regions sharing sequence, molecular size and pI value similarity. Both of VvDAHPSs had a close evolution relationship with Populus trichocarpa DAHPSs. The prokaryotically-expressed VvDAHPSs both manifested DAHPS catalytic activity and Mn(2+)-activated effects. Analysis by real time-PCR showed that VvDAHPS-1 and VvDAHPS-2 were expressed in all the tested tissues, but their expression patterns accompanying with berry mature varied in the skin, pulp and seeds. The results give new insight into further study on regulatory mechanism of grape phenolics biosynthesis.