Carotenoid-induced non-photochemical quenching in the cyanobacterial chlorophyll synthase-HliC/D complex

0467874 - MBÚ 2017 RIV NL eng J - Journal Article
Niedzwiedzki, D.M. - Tronina, T. - Liu, H. - Staleva, H. - Komenda, Josef - Sobotka, Roman - Blankenship, R.E. - Polívka, T.
Carotenoid-induced non-photochemical quenching in the cyanobacterial chlorophyll synthase-HliC/D complex.
Biochimica Et Biophysica Acta-Bioenergetics. Roč. 1857, č. 9 (2016), s. 1430-1439. ISSN 0005-2728. E-ISSN 1879-2650
R&D Projects: GA ČR GBP501/12/G055
Institutional support: RVO:61388971
Keywords : Carotenoids * Non-photochemical quenching * Energy transfer
Subject RIV: CE - Biochemistry
Impact factor: 4.932, year: 2016

Chl synthase (ChlG) is an important enzyme of the Chl biosynthetic pathway catalyzing attachment of phytol/geranylgeraniol tail to the chlorophyllide molecule. Here we have investigated the Flag-tagged ChlG (f.ChlG) in a complex with two different high-light inducible proteins (Hlips) HliD and HliC. The f.ChlG-Hlips complex binds a Chl alpha and three different carotenoids, beta-carotene, zeaxanthin and myxoxanthophyll. Application of ultra fast time-resolved absorption spectroscopy performed at room and cryogenic temperatures revealed excited state dynamics of complex-bound pigments. After excitation of Chl alpha in the complex, excited Chl a is efficiently quenched by a nearby carotenoid molecule via energy transfer from the Chl alpha Q(y) state to the carotenoid S-1 state. The kinetic analysis of the spectroscopic data revealed that quenching occurs with a time constant of similar to 2 ps and its efficiency is temperature independent. Even though due to its long conjugation myxoxanthophyll appears to be energetically best suited for role of Chl alpha quencher, based on comparative analysis and spectroscopic data we propose that beta-carotene bound to Hlips acts as the quencher rather than myxoxanthophyll and zeaxanthin, which are bound at the f.ChlG and Hlips interface. The S-1 state lifetime of the quencher has been determined to be 13 ps at room temperature and 21 ps at 77 K. These results demonstrate that Hlips act as a conserved functional module that prevents photodamage of protein complexes during photosystem assembly or Chl biosynthesis.
Permanent Link: http://hdl.handle.net/11104/0266195