Fig. 1.

Chl biosynthesis pathway in cyanobacteria. Intermediates in the Mg branch of cyanobacterial Chl biosynthesis are shown in bold. The steps at which two distinct enzymes differentially operate are shown with two arrows. Demetalated derivatives from intermediates of the Mg-branch are shown by thin arrows on the right. Pheophytin a (in PSII) is produced from Chl and could be another precursor for the production of Pheobide (indicated by a dashed arrow). GGPP and Phytyl-PP are geranylgeranyl pyrophosphate and phytyl pyrophosphate, respectively.