Energy dissipation mechanisms in the FCPb light-harvesting complex of the diatom Cyclotella meneghiniana.

Energy dissipation mechanisms in the FCPb light-harvesting complex of the diatom Cyclotella meneghiniana. Biochim Biophys Acta. 2018 Jul 26;: Authors: Elnour HMAM, Dietzel L, Ramanan C, Büchel C, van Grondelle R, Krüger TPJ Abstract Transient absorption spectroscopy has been applied to investigate the energy dissipation mechanisms in the nonameric fucoxanthin-chlorophyll-a,c-binding protein FCPb of the centric diatom Cyclotella meneghiniana. FCPb complexes in their unquenched state were compared with those in two types of quenching environments, namely aggregation-induced quenching by detergent removal, and clustering via incorporation into liposomes. Applying global and target analysis, in combination with a fluorescence lifetime study and annihilation calculations, we were able to resolve two quenching channels in FCPb that involve chlorophyll-a pigments for FCPb exposed to both quenching environments. The fast quenching channel operates on a timescale of tens of picoseconds and exhibits similar spectral signatures as the unquenched state. The slower quenching channel operates on a timescale of tens to hundreds of picoseconds, depending on the degree of quenching, and is characterized by enhanced population of low-energy states between 680 and 710 nm. The results indicate that FCPb is, in principle, able to function as a dissipater of excess energy and can do this in vitro even more efficiently than the homologous FCPa complex,...
Source: Biochimica et Biophysica Acta - Category: Biochemistry Authors: Tags: Biochim Biophys Acta Source Type: research