Isolation and spectral characterization of Photosystem II reaction center from Synechocystis sp. PCC 6803

Abstract

We isolated highly-purified photochemically active photosystem (PS) II reaction center (RC) complexes from the cyanobacterium Synechocystis sp. PCC 6803 using a histidine-tag introduced to the 47 kDa chlorophyll protein, and characterized their spectroscopic properties. Purification was carried out in a one-step procedure after isolation of PS II core complex. The RC complexes consist of five polypeptides, the same as in spinach. The pigment contents per two molecules of pheophytin a were 5.8 +/- 0.3 chlorophyll (Chl) a and 1.8 +/- 0.1 beta-carotene; one cytochrome b(559) was found per 6.0 Chl a molecules. Overall absorption and fluorescence properties were very similar to those of spinach PS II RCs; our preparation retains the best properties so far isolated from cyanobacteria. However, a clear band-shift of pheophytin a and beta-carotene was observed. Reasons for these differences, and RC composition, are discussed on the basis of the three-dimensional structure of complexes.

Discovery of a Chlorophyll Binding Protein Complex Involved in the Early Steps of Photosystem II Assembly in Synechocystis

“…The absorption spectrum of the RCII* separated by native gel electrophoresis indicated the presence of a higher number of chlorophyll and b-carotene molecules in comparison with the RCII complex previously isolated from Synechocystis by stripping off the inner PSII antennae from the PSII core (Tomo et al, 2008), which is consistent with additional binding of pigments to the Ycf39-Hlip complex. Moreover, a small shoulder at ;545 nm is consistent with the presence of pheophytin.…”

Fluorescence Emission from the Photosynthetic Apparatus

“…Discrepant results have been published for the reduced Pheo at low temperature. Thus Pheo D1 has been assigned Q y maxima at ~670-672 (Braun et al, 1990;Konermann and Holzwarth, 1996;Tomo et al, 2008), and at ~681-685 nm (Stewart et al, 2000).…”

“…The absorption spectra encompass contributions of all chromophores in these complexes, namely Chls a (B xy ~435 nm, Q x ~ 625 nm, Q y ~ 668-672 nm), Pheos a (B xy ~ 416 nm, Q x ~ 540 nm, Q y ~ 669-681 nm) and b-Cars (~450-500 nm). Characteristic is the Soret (B xy ) absorption maximum of PSII RC at 416 nm (because of the higher Pheo a proportion; Tomo et al, 2008) and the higher energy Q y band of CP43 (668 nm; Alfonso et al, 1994;Dekker et al, 1995;Groot et al, 1999) relative to those in CP47 (671 nm;Alfonso et al, 1994;Chang et al,1994;Dekker et al, 1995;Groot et al, 1995) and in D1D2 (672 nm; Konermann and Holzwarth, 1996). At cryogenic temperatures, absorption bands become sharper and may split into two peaks.…”

Flow cytometry as a valuable tool to study cyanobacteria:A mini-review

“…The reaction center (RC) complex for initial charge separation is in the center of PS II surrounded laterally by peripheral light-harvesting antenna pigment-protein complexes (Adir 2005;Tomo et al 2008). They are both located within the same plane of the thylakoid membrane.…”