Energy transfer pathways in the CAC light-harvesting complex of Rhodomonas salina

0536787 - MBÚ 2021 RIV NL eng J - Journal Article
Šebelík, V. - West, R. - Trsková, Eliška - Kaňa, Radek - Polívka, T.
Energy transfer pathways in the CAC light-harvesting complex of Rhodomonas salina.
Biochimica Et Biophysica Acta-Bioenergetics. Roč. 1861, č. 11 (2020), č. článku 148280. ISSN 0005-2728. E-ISSN 1879-2650
R&D Projects: GA ČR(CZ) GA19-11494S
Institutional support: RVO:61388971
Keywords : Peridinin * Carotenoids * Chlorophyll Binding Proteins
OECD category: Microbiology
Impact factor: 3.991, year: 2020
Method of publishing: Limited access
https://www.sciencedirect.com/science/article/pii/S0005272820301304

Photosynthetic organisms had to evolve diverse mechanisms of light-harvesting to supply photosynthetic apparatus with enough energy. Cryptophytes represent one of the groups of photosynthetic organisms combining external and internal antenna systems. They contain one type of immobile phycobiliprotein located at the lumenal side of the thylakoid membrane, together with membrane-bound chlorophyll a/c antenna (CAC). Here we employ femtosecond transient absorption spectroscopy to study energy transfer pathways in the CAC proteins of cryptophyte Rhodomonas salina. The major CAC carotenoid, alloxanthin, is a cryptophyte-specific carotenoid, and it is the only naturally-occurring carotenoid with two triple bonds in its structure. In order to explore the energy transfer pathways within the CAC complex, three excitation wavelengths (505, 590, and 640 nm) were chosen to excite pigments in the CAC antenna. The excitation of Chl c at either 590 or 640 nm proves efficient energy transfer between Chl c and Chl a. The excitation of alloxanthin at 505 nm shows an active pathway from the S2 state with efficiency around 50%, feeding both Chl a and Chl c with approximately 1:1 branching ratio, yet, the S1-route is rather inefficient. The 57 ps energy transfer time to Chl a gives ~25% efficiency of the S1 channel. The low efficiency of the S1 route renders the overall carotenoid-Chl energy transfer efficiency low, pointing to the regulatory role of alloxanthin in the CAC antenna.
Permanent Link: http://hdl.handle.net/11104/0314552