Chlorophyll d'/PS1 stoichiometry in a chlorophyll d-dominated cyanobacterium Acaryochloris marina

Abstract

In Acaryochloris marina, Chl d' and Phe a were detected as minor pigments, in addition to the major Chl d, while neither Chl a' nor Phe d were detected. On the basis of Phe a/PS2 = 2, a combination of Chl d'/Phe a = 0.4 and PS1/PS2 = 0.8 led to Chl d'/PS1 = 1. These indicate the primary electron donor of PS1 of A. marina, might be a heterodimer of Chl d/d'. Chl a content of A. marina is dependent on light intensity. The minimum ratio of Chl a/Phe a was 2/2, indicating the primary electron donor of PS2 is (Chl a )₂, the accessory is Chl d, and the primary electron acceptor is Phe a. The primary charge separation initiated from accessory Chl d is theoretically possible, after moderately uphill energy transfer from antenna Chl d to accessory Chl d.