Figure 1.

The MEP and Tetrapyrrole Pathways Collaborate in Chlorophyll Biosynthesis.

Abbreviated skeletons of the pathways are shown, with steps of particular relevance to this study labeled. Note that only a subset of the intermediates and products are shown for each pathway, and dotted lines indicate several biochemical steps. Of relevance to chlorophyll synthesis, the MEP pathway generates GGPP isoprenoid and the tetrapyrrole pathway produces chlorophyllide. Chemical inhibitors used in this study are shown: FSM inhibits DXR; gabaculine (GC) inhibits glutamate semialdehyde aminotransferase (GSA-AT); and oxyfluorfen (OXF) inhibits protoporphyrinogen oxidase (PPOX). The names of proteins analyzed in this study through use of mutants are in boxes located near pathway step in which the encoded proteins work. ppi1 is the name of the mutant defective in TOC33. The figure also illustrates that exogenous phytol can be incorporated into chlorophyll after phosphorylation.

[See online article for color version of this figure.]