Observation of the solid-state photo-CIDNP effect in entire cells of cyanobacteria Synechocystis

Abstract

Cyanobacteria are widely used as model organism of oxygenic photosynthesis due to being the simplest photosynthetic organisms containing both photosystem I and II (PSI and PSII). Photochemically induced dynamic nuclear polarization (photo-CIDNP) 13C magic-angle spinning (MAS) NMR is a powerful tool in understanding the photosynthesis machinery down to atomic level. Combined with selective isotope enrichment this technique has now opened the door to study primary charge separation in whole living cells. Here, we present the first photo-CIDNP observed in whole cells of the cyanobacterium Synechocystis.

Photo-CIDNP in the Reaction Center of the Diatom Cyclotella meneghiniana Observed by 13C MAS NMR

“…[17] Especially the similarity of the spectra reported in this work to those from S. oleracea [20] is remarkable. In the work on spinach, eleven lightinduced signals were observed and also assigned to a single Chl a donor cofactor.…”

“…The solid-state photo-CIDNP effect also has been observed in 13 C-labeled samples of Synechocystis sp. on cells without further isolation at 4.7 T. [17] Eight light-induced signals have been observed but not assigned to the cofactors of either PS I or PS II. Since all light-induced signals are emissive, it was however assumed that they originate from PS I.…”

“…[14] Another proteobacterium: Rhodopseudomonas acidophilia [15] has been demonstrated to show the effect as well as Chlorobium tepidum [16] from the chlorobi phylum, Synechocystis sp. PCC 6803 [17] -a cyanobacterium -and the firmicute Heliobacillus mobilis. [18] Additionally, there are two more bacterial phyla which contain phototrophic members: chloroflexi and acidobacteria.…”

Photochemically Induced Dynamic Nuclear Polarization Observed by Solid-State NMR in a Uniformly 13C-Isotope-Labeled Photosynthetic Reaction Center

“…frozen natural photosynthetic systems, where it allows for detailed functional analysis 4,5,6,3,7 , as well as a blue-light photoreceptor LOV1-C57S 8,9 . Since all natural photosynthetic systems tested have shown the effect, it has been proposed that the solid-state photo-CIDNP effect is related to the unsurpassed efficiency of natural photosynthetic electron transfer 10 .…”

The Solid-State Photo-CIDNP Effect and Its Analytical Application

“…Such strong signal enhancement allows, for example, selectively observing photosynthetic cofactors to form radical-pairs at nanomolar concentrations in membranes, cells [3,4] and entire plants (G.J. Janssen et al, unpublished).…”