Details

Autor(en) / Beteiligte

• Akhtar, Parveen
• Lingvay, Mónika
• Kiss, Teréz
• Deák, Róbert
• Bóta, Attila
• Ughy, Bettina
• Garab, Győző
• Lambrev, Petar H.

Titel

Excitation energy transfer between Light-harvesting complex II and Photosystem I in reconstituted membranes

Ist Teil von

• Biochimica et biophysica acta, 2016-04, Vol.1857 (4), p.462-472

Ort / Verlag

Netherlands: Elsevier B.V

Erscheinungsjahr

2016

Link zum Volltext

Quelle

EZB Electronic Journals Library

Beschreibungen/Notizen

• Light-harvesting complex II (LHCII), the major peripheral antenna of Photosystem II in plants, participates in several concerted mechanisms for regulation of the excitation energy and electron fluxes in thylakoid membranes. In part, these include interaction of LHCII with Photosystem I (PSI) enhancing the latter's absorption cross-section – for example in the well-known state 1 – state 2 transitions or as a long-term acclimation to high light. In this work we examined the capability of LHCII to deliver excitations to PSI in reconstituted membranes in vitro. Proteoliposomes with native plant thylakoid membrane lipids and different stoichiometric ratios of LHCII:PSI were reconstituted and studied by steady-state and time-resolved fluorescence spectroscopy. Fluorescence emission from LHCII was strongly decreased in PSI–LHCII membranes due to trapping of excitations by PSI. Kinetic modelling of the time-resolved fluorescence data revealed the existence of separate pools of LHCII distinguished by the time scale of energy transfer. A strongly coupled pool, equivalent to one LHCII trimer per PSI, transferred excitations to PSI with near-unity efficiency on a time scale of less than 10ps but extra LHCIIs also contributed significantly to the effective antenna size of PSI, which could be increased by up to 47% in membranes containing 3 LHCII trimers per PSI. The results demonstrate a remarkable competence of LHCII to increase the absorption cross-section of PSI, given the opportunity that the two types of complexes interact in the membrane. [Display omitted] •Light-harvesting complex II efficiently transfers energy to Photosystem I in vitro.•Kinetic model of PSI–LHCII fits the time-resolved fluorescence data.•Energy transfer occurs on time scales of less than 10ps to hundreds of ps.•Energetic coupling increased the effective absorption cross-section of PSI.