Journal Article

M-type thioredoxins are involved in the xanthophyll cycle and proton motive force to alter NPQ under low-light conditions in Arabidopsis

Liu, Bing, Da, Qingen, Sun, Ting, Wang, Hong-Bin, Wang, Menglong, Jin, Honglei, Feng, Dongru, Li, Mengshu, Wang, Jinfa

2018

Overview

Key message M-type thioredoxins are required to regulate zeaxanthin epoxidase activity and to maintain the steady-state level of the proton motive force, thereby influencing NPQ properties under low-light conditions in Arabidopsis . Non-photochemical quenching (NPQ) helps protect photosynthetic organisms from photooxidative damage via the non-radiative dissipation of energy as heat. Energy-dependent quenching (qE) is a major constituent of NPQ. However, the mechanism underlying the regulation of qE is not well understood. In this study, we demonstrate that the m-type thioredoxins TRX-m1, TRX-m2, and TRX-m4 (TRX-ms) interact with the xanthophyll cycle enzyme zeaxanthin epoxidase (ZE) and are required for maintaining the redox-dependent stabilization of ZE by regulating its intermolecular disulfide bridges. Reduced ZE activity and accumulated zeaxanthin levels were observed under TRX-ms deficiency. Furthermore, concurrent deficiency of TRX-ms resulted in a significant increase in proton motive force (pmf) and acidification of the thylakoid lumen under low irradiance, perhaps due to the significantly reduced ATP synthase activity under TRX-ms deficiency. The increased pmf, combined with acidification of the thylakoid lumen and the accumulation of zeaxanthin, ultimately contribute to the elevated stable qE in VIGS–TRX-m2m4/m1 plants under low-light conditions. Taken together, these results indicate that TRX-ms are involved in regulating NPQ-dependent photoprotection in Arabidopsis .

• Publisher: Springer Berlin Heidelberg,Springer Nature B.V
• Subject: Acidification / Arabidopsis / Arabidopsis - metabolism / Arabidopsis Proteins - metabolism / ATP synthase / autotrophs / Biomedical and Life Sciences / Biotechnology / Cell Biology / Chlorophyll - metabolism / Chloroplast Thioredoxins - metabolism / disulfide bonds / energy / enzyme activity / H+/K+-exchanging ATPase / H-transporting ATP synthase / heat / Irradiance / Life Sciences / Light / light intensity / lutein / Original Article / Oxidation-Reduction / Oxidoreductases - metabolism / Photochemicals / photolysis / photostability / Photosynthesis / Photosynthesis - radiation effects / Plant Biochemistry / Plant Sciences / Protein Binding / proton-motive force / Proton-Motive Force - radiation effects / Protonmotive force / Protons / Quenching / thioredoxins / thylakoids / Thylakoids - metabolism / Xanthophylls / Xanthophylls - metabolism / Zeaxanthin / Zeaxanthin epoxidase / Zeaxanthins - metabolism