Chloroplast biogenesis 89: development of analytical tools for probing the biosynthetic topography of photosynthetic membranes by determination of resonance excitation energy transfer distances separating metabolic tetrapyrrole donors from chlorophyll a acceptors.

Abstract The thorough understanding of photosynthetic membrane assembly requires a deeper knowledge of the coordination and regulation of the chlorophyll (Chl) and thylakoid apoprotein biosynthetic pathways. As a working hypothesis we have recently proposed three different Chl–thylakoid apoprotein biosynthesis models: a single-branched Chl biosynthetic pathway (SBP)–single location model, a SBP–multilocation model, and a multibranched Chl biosynthetic pathway (MBP)–sublocation model [Handbook of Photochemistry and Photobiology, American Scientific Publishers, Los Angeles, 2003, p. 183]. The detection of resonance excitation energy transfer between tetrapyrrole precursors of Chl, and several Chl–protein complexes [Photochem. Photobiol. 78 (2003) 184], has made it possible to test the validity of the proposed Chl–thylakoid apoprotein biosynthesis models by resonance excitation energy transfer determinations. In this work, resonance excitation energy transfer techniques that allow the determination of distances separating tetrapyrrole donors from Chl–protein acceptors in green plants by using readily available electronic spectroscopic instrumentation are developed. It is concluded that the calculated distances are compatible with the MBP–sublocation model and incompatible with the operation of the SBP–single location Chl–protein biosynthesis model.