Abstract
Acaryochloris spp. contains chlorophyll (Chl) d as a major Chl, and can utilize far-red light for photosynthesis. To alter the function of photosystems (PSs), a metabolic engineering approach is an effective way because the properties of PSs primarily depend on the Chl species used. However, lack of a genetic technique prevented us from altering the metabolic pathway of Chl in Acaryochloris. Recently, we developed the transformation system of A. marina MBIC 11017, and produced a transformant expressing chlorophyllide a oxygenase gene that involved in Chl b biosynthesis. The resultant transformant accumulated a novel Chl (7-formyl-Chl dP) in addition to Chl dP and Chl aP. In this study, we isolated the PS I and PS II complexes from both the transformant and a control strain. Polypeptide compositions of PSs from the transformant were similar to those of PSs from the control strain. Low temperature absorption spectra of purified PSs revealed that part of Chl d molecules were replaced by the novel Chl. Furthermore, by the low temperature fluorescence spectra, we found the energy transfer from the novel Chl to Chl d. The function of the novel Chl in PSs will be discussed.
