The Characterization of Photosystem I in a Chlorophyll d-dominated Cyanobacterium

Abstract

Acaryochloris marina is a unique cyanobacterium that produces chlorophyll (Chl) d as a major photosynthetic pigment. Recently, the complete genome sequence of A. marina MBIC 11017 was determined, and the PsaI was not found in the genome. The crystal analysis of PS I showed that PsaI is localized in the attaching site of individual monomers. We identified a new subunit and plural PsaK subunits in the PS I complexes of A. marina. We presumed that this new subunit might replace the function of PsaI in A. marina. In PS I, the redox potential of the primary electron donor (P740) and localization of Chl a are still controversial. We estimated a redox potential of P740 and found that it was inconsistent with previous report (Hu et al. 1998). Based on these observations, the assignment of the pigment and its role of PS I will be discussed.