Dissecting and modeling zeaxanthin- and lutein-dependent nonphotochemical quenching in Arabidopsis thaliana

Abstract

Photosynthetic organisms use various photoprotective mechanisms to dissipate excess photoexcitation as heat in a process called nonphotochemical quenching (NPQ). Regulation of NPQ allows for a rapid response to changes in light intensity and in vascular plants, is primarily triggered by a pH gradient across the thylakoid membrane (∆pH). The response is mediated by the PsbS protein and various xanthophylls. Time-correlated single-photon counting (TCSPC) measurements were performed on to quantify the dependence of the response of NPQ to changes in light intensity on the presence and accumulation of zeaxanthin and lutein. Measurements were performed on WT and mutant plants deficient in one or both of the xanthophylls as well as a transgenic line that accumulates lutein via an engineered lutein epoxide cycle. Changes in the response of NPQ to light acclimation in WT and mutant plants were observed between two successive light acclimation cycles, suggesting that the character of the rapid and reversible response of NPQ in fully dark-acclimated plants is substantially different from in conditions plants are likely to experience caused by changes in light intensity during daylight. Mathematical models of the response of zeaxanthin- and lutein-dependent reversible NPQ were constructed that accurately describe the observed differences between the light acclimation periods. Finally, the WT response of NPQ was reconstructed from isolated components present in mutant plants with a single common scaling factor, which enabled deconvolution of the relative contributions of zeaxanthin- and lutein-dependent NPQ.

Changing Form and Function through Carotenoids and Synthetic Biology

“…Some carotenoids are interconverted through epoxidase/de-epoxidase activities, such as activities which control the formation of energetically optimal pigments for photoprotection (Leonelli et al, 2017;Leuenberger et al, 2017). Carotenoid epoxides also form nonenzymatically, as a consequence of saturating light intensities during photosynthesis.…”

Over-Expression of LcPDS, LcZDS, and LcCRTISO, Genes From Wolfberry for Carotenoid Biosynthesis, Enhanced Carotenoid Accumulation, and Salt Tolerance in Tobacco

“…As essential secondary metabolites, carotenoids have been implicated in a large number of biological functions of plant growth and development. In photosystem II (PS II), carotenoids transfer energy to the reaction center (Bassi et al, 1993;Amarnath et al, 2016) and protect chlorophyll from excessive energy by sequestering single oxygen (Di Mascio et al, 1989;Ramel et al, 2012;Ruban, 2016;Leuenberger et al, 2017). Meanwhile, carotenoids play roles in protecting plants from oxidative damages as effective antioxidants (Truscott, 1990).…”

First evidence of freezing tolerance in a resurrection plant: insights into molecular mobility and zeaxanthin synthesis in the dark

“…This two‐step reaction has been traditionally considered to be light‐dependent and can be reverted by a third enzyme: zeaxanthin epoxidase (ZE), which epoxidates Z back to V, closing the so‐called xanthophyll or V‐cycle (Müller et al , Ruban et al , Demmig‐Adams et al , Jahns and Holzwarth , Dall'Osto et al ). The conversion of V to Z is associated with conformational changes in the antennae and with enhanced dissipation of energy as heat (NPQ), that overall have a vital photoprotective role in the photosynthetic apparatus (Demmig‐Adams , Johnson et al , Leuenberger et al ). This cycle adjusts dynamically the efficiency of light energy conversion to fit the actual demand of metabolic energy, thereby protecting the photosynthetic apparatus from photodamage.…”