Fluorescence Properties of the CP43-deletion Mutant in Synechocystis sp. PCC 6803.

Abstract

Photosystem (PS) II consists of D1, D2, CP43, CP47, and other many small subunits, and is responsible for the water oxidation reaction. It is known that PS II fluoresces at 685 and 695 nm at 77K, and CP43 and CP47 are attributed to their origins, respectively. We constructed the CP43-deletion mutant of Synechocystis sp. PCC 6803 by replacement the gene (psbC) with the antibiotics resistant gene. This strain could not grow autotrophically but grow under the presence of 5 mM glucose with the following two light conditions, i.e. photo-mixotrophic growth with a continuous light and light-activated heterotrophic growth with illumination of light for 15 min per day. This strain showed two fluorescence maxima at 686 and 725 nm at 77K, and the former might come from phycobiliproteins. The time-resolved fluorescence spectra gave essentially identical results. Based on these observations, fluorescence properties will be discussed in details.