The diadinoxanthin diatoxanthin cycle induces structural rearrangements of the isolated FCP antenna complexes of the pennate diatom Phaeodactylum tricornutum

Diadinoxanthin de‐epoxidation as important factor in the short‐term stabilization of diatom photosynthetic membranes exposed to different temperatures

“…These changes include, on the one hand, the lateral diffusion of the proteins during detachment and aggregation of the FCPs, and, on the other hand, the lateral diffusion of Dtx between MGDG domains, bilayer phases, and the protein binding sites (Figure ). It has been already shown that Dtx‐dependent aggregation of FCPs can also take place in darkness at low pH and is comparable with process under high light (the same shift of the fluorescence emission of the aggregated FCP complexes, that is, from 680 to 705/710 nm, as the shift during the formation of NPQ quenching site Q1 in illuminated diatom cells; Schaller‐Laudel et al, ). According to our results, these intensive protein and pigment movements in the membrane during Dtx synthesis result in temporary seal of the polar region of the membrane visible as an increase of the GP values of the Laurdan fluorescence (Figure ), the S parameter calculated for 5‐SASL (Figure ) and the strong movement restrictions of the 16‐SASL molecules detected as τ 2C (Figure c).…”

Influence of thylakoid membrane lipids on the structure of aggregated light‐harvesting complexes of the diatom Thalassiosira pseudonana and the green alga Mantoniella squamata

“…The pennate diatom P . tricornutum , on the other hand, does not show FCP‐A and FCP‐B complexes and the MW of the two dominant FCP apoproteins is found in the range of 17–19 kDa (Schaller‐Laudel et al ), which is slightly lower than that observed for the FCP apoproteins of T . pseudonana in the present study.…”

“…The stronger contribution of long‐wavelength components resulted in a F700/F680 value of around 0.6 whereas for the DM FCP a value of only around 0.3 was calculated. As higher values of F700/F680 indicate a higher aggregation state of LHCs (Schaller et al , Schaller et al , Schaller‐Laudel et al ), it can be concluded that the SCP FCP exists in an aggregated state. This is in line with the lower blue to red absorption ratios of the SCP FCP.…”

“…Comparable results have been obtained for FCP preparations of P . tricornutum (Schaller et al , Schaller‐Laudel et al ). The F700/F680 ratios of the lipid‐treated SCP FCPs did not differ from those of the control SCP FCP at pH 8.…”

The diatom Phaeodactylum tricornutum adjusts nonphotochemical fluorescence quenching capacity in response to dynamic light via fine‐tuned Lhcx and xanthophyll cycle pigment synthesis

“…It is assumed that Lhcx proteins bind Dd and Dt (Beer et al, 2006;Lepetit et al, 2013) and they apparently influence the supramolecular organisation of the antenna complexes (Ghazaryan et al, 2016). The location of Lhcx within thylakoids remains ambiguous as based on contrasting reports of both FCP (Beer et al, 2006;Lepetit et al, 2010;Grouneva et al, 2011;Nagao et al, 2013;Schaller-Laudel et al, 2015) and PSI association (Grouneva et al, 2011). The current NPQ model proposes two major quenching sites in diatoms (Miloslavina et al, 2009;Chukhutsina et al, 2014;Lavaud & Goss, 2014;Derks et al, 2015;Goss & Lepetit, 2015): Quenching site 1 is mechanistically independent of Dt (Chukhutsina et al, 2014) and is formed rapidly mainly by detached, oligomeric antenna complexes due to build-up of the DpH, while quenching site 2 is located close to the PSII reaction centres and is directly dependent on Dt formation.…”