Carotenoid to bacteriochlorophyll energy transfer in the RC-LH1-PufX complex from Rhodobacter sphaeroides containing the extended conjugation keto-carotenoid diketospirilloxanthin

0495138 - BC 2019 RIV NL eng J - Článek v odborném periodiku
Šlouf, V. - Kesan, G. - Litvín, Radek - Swainsbury, D.J. K. - Martin, E.C. - Hunter, C.N. - Polívka, Tomáš
Carotenoid to bacteriochlorophyll energy transfer in the RC-LH1-PufX complex from Rhodobacter sphaeroides containing the extended conjugation keto-carotenoid diketospirilloxanthin.
Photosynthesis Research. Roč. 135, č. 1-3 (2018), s. 33-43. ISSN 0166-8595. E-ISSN 1573-5079
Grant CEP: GA ČR(CZ) GBP501/12/G055
Institucionální podpora: RVO:60077344
Klíčová slova: light-harvesting complex * ultrafast dynamics * crystal-structure * excited-states
Obor OECD: Biophysics
Impakt faktor: 3.057, rok: 2018

RC-LH1-PufX complexes from a genetically modified strain of Rhodobacter sphaeroides that accumulates carotenoids with very long conjugation were studied by ultrafast transient absorption spectroscopy. The complexes predominantly bind the carotenoid diketospirilloxanthin, constituting about 75% of the total carotenoids, which has 13 conjugated C=C bonds, and the conjugation is further extended to two terminal keto groups. Excitation of diketospirilloxanthin in the RC-LH1-PufX complex demonstrates fully functional energy transfer from diketospirilloxanthin to BChl a in the LH1 antenna. As for other purple bacterial LH complexes having carotenoids with long conjugation, the main energy transfer route is via the S-2-Q(x) pathway. However, in contrast to LH2 complexes binding diketospirilloxanthin, in RC-LH1-PufX we observe an additional, minor energy transfer pathway associated with the S-1 state of diketospirilloxanthin. By comparing the spectral properties of the S-1 state of diketospirilloxanthin in solution, in LH2, and in RC-LH1-PufX, we propose that the carotenoid-binding site in RC-LH1-PufX activates the ICT state of diketospirilloxanthin, resulting in the opening of a minor S-1/ICT-mediated energy transfer channel.
Trvalý link: http://hdl.handle.net/11104/0288150