LIGHT-HARVESTING IN ACARYOCHLORIS-MARINA - SPECTROSCOPIC CHARACTERIZATION OF A CHLOROPHYLL D-DOMINATED PHOTOSYNTHETIC ANTENNA SYSTEM

Oxygenic photosynthesis of the prokaryote Acaryochloris marina involve s chlorophyll d (Chl d) as the major pigment [Miyashita et al, (1996) Nature 383, 402], Four spectral forms of Chl d (peak wavelengths: 694, 714, 726 and 740 nm) are resolvable by low-temperature absorption spe ctroscopy on intact cells, Based on fluorescence spectra (at 290 K and 77 K) and on analysis of fluorescence induction curves we conclude: ( 1) excitation energy is efficiently transferred between the various sp ectral forms of Chl d and the PS II reaction center; (2) Chl d serves as a light-harvesting pigment for both, Photosystem II (PS II) and PS I; (3) excitation energy transfer between PS II units occurs. (C) 1997 Federation of European Biochemical Societies.