A novel phytyltransferase from Synechocystis sp PCC 6803 involved in tocopherol biosynthesis

The deduced polypeptide sequence of open reading frame slr1736 reveals homo logy to chlorophyll synthase and 1,4-dihdroxy-2-naphthoic acid phytyltransf erase in Synechocystis sp, strain PCC 6803. In tocopherol and plastoquinone biosynthesis, a condensation reaction mechanistically similar to that of t hese two enzymes is performed. To analyze the function of this novel prenyl transferase, a deletion mutant of slr1736 was generated bg homologous recom bination. The mutant showed a markedly decreased tocopherol content, while plasto-quinone levels remained unchanged. Since the aromatic precursor homo gentisic acid accumulated in the mutant, the function of the enzyme was pro ven to he a novel tocophcrol phytyltransferase. (C) 2001 Federation of Euro pean Biochemical Societies. Published by Elsevier Science B.V. All rights r eserved.