The role of xanthophylls in the supramolecular organization of the photosynthetic complex LHCII in lipid membranes studied by high-resolution imaging and nanospectroscopy

Publication date: Available online 14 November 2019Source: Biochimica et Biophysica Acta (BBA) - BioenergeticsAuthor(s): Jiangtao Zhou, Sergey Sekatskii, Renata Welc, Giovani Dietler, Wieslaw I. GruszeckiAbstractThe xanthophyll cycle is a regulatory mechanism operating in the photosynthetic apparatus of plants. It consists of the conversion of the xanthophyll pigment violaxanthin to zeaxanthin, and vice versa, in response to light intensity. According to the current understanding, one of the modes of regulatory activity of the cycle is associated with the influence on a molecular organization of pigment-protein complexes. In the present work, we analyzed the effect of violaxanthin and zeaxanthin on the molecular organization of the LHCII complex, in the environment of membranes formed with chloroplast lipids. Nanoscale imaging based on atomic force microscopy (AFM) showed that the presence of exogenous xanthophylls promotes the formation of the protein supramolecular structures. Nanoscale infrared (IR) absorption analysis based on AFM-IR nanospectroscopy suggests that zeaxanthin promotes the formation of LHCII supramolecular structures by forming inter-molecular β-structures. Meanwhile, the molecules of violaxanthin act as “molecular spacers” preventing self-aggregation of the protein, potentially leading to uncontrolled dissipation of excitation energy in the complex. This latter mechanism was demonstrated with the application of fluorescence lifetime imaging microscopy...
Source: Biochimica et Biophysica Acta (BBA) Bioenergetics - Category: Biochemistry Source Type: research