Maithili Krishnan-Schmieden1, Patrick E Konold2, John T M Kennis3, Anjali Pandit4. 1. Dept. of Solid-State NMR, Leiden Inst. of Chemistry, Leiden University, Leiden, The Netherlands. 2. Department of Physics and Astronomy, Faculty of Sciences, Vrije Universiteit, Amsterdam, The Netherlands. 3. Department of Physics and Astronomy, Faculty of Sciences, Vrije Universiteit, Amsterdam, The Netherlands. j.t.m.kennis@vu.nl. 4. Dept. of Solid-State NMR, Leiden Inst. of Chemistry, Leiden University, Leiden, The Netherlands. a.pandit@chem.leidenuniv.nl.
Abstract
Plants need to protect themselves from excess light, which causes photo-oxidative damage and lowers the efficiency of photosynthesis. Photosystem II subunit S (PsbS) is a pH sensor protein that plays a crucial role in plant photoprotection by detecting thylakoid lumen acidification in excess light conditions via two lumen-faced glutamates. However, how PsbS is activated under low-pH conditions is unknown. To reveal the molecular response of PsbS to low pH, here we perform an NMR, FTIR and 2DIR spectroscopic analysis of Physcomitrella patens PsbS and of the E176Q mutant in which an active glutamate has been replaced. The PsbS response mechanism at low pH involves the concerted action of repositioning of a short amphipathic helix containing E176 facing the lumen and folding of the luminal loop fragment adjacent to E71 to a 310-helix, providing clear evidence of a conformational pH switch. We propose that this concerted mechanism is a shared motif of proteins of the light-harvesting family that may control thylakoid inter-protein interactions driving photoregulatory responses.
Plants need to protect themselves from excess light, which causes photo-oxidative damage and lowers the efficiency of photosynthesis. Photosystem II subunit S (n class="Gene">PsbS) is a pH sensor protein that plays a crucial role in plant photoprotection by detecting thylakoid lumen acidification in excess light conditions via two lumen-faced glutamates. However, how PsbS is activated under low-pH conditions is unknown. To reveal the molecular response of PsbS to low pH, here we perform an NMR, FTIR and 2DIR spectroscopic analysis of Physcomitrella patensPsbS and of the E176Q mutant in which an active glutamate has been replaced. The PsbS response mechanism at low pH involves the concerted action of repositioning of a short amphipathic helix containing E176 facing the lumen and folding of the luminal loop fragment adjacent to E71 to a 310-helix, providing clear evidence of a conformational pH switch. We propose that this concerted mechanism is a shared motif of proteins of the light-harvesting family that may control thylakoid inter-protein interactions driving photoregulatory responses.
Authors: Rameez Arshad; Francesco Saccon; Pushan Bag; Avratanu Biswas; Claudio Calvaruso; Ahmad Farhan Bhatti; Steffen Grebe; Vincenzo Mascoli; Moontaha Mahbub; Fernando Muzzopappa; Alexandros Polyzois; Christo Schiphorst; Mirella Sorrentino; Simona Streckaité; Herbert van Amerongen; Eva-Mari Aro; Roberto Bassi; Egbert J Boekema; Roberta Croce; Jan Dekker; Rienk van Grondelle; Stefan Jansson; Diana Kirilovsky; Roman Kouřil; Sylvie Michel; Conrad W Mullineaux; Klára Panzarová; Bruno Robert; Alexander V Ruban; Ivo van Stokkum; Emilie Wientjes; Claudia Büchel Journal: Plant Physiol Date: 2022-06-27 Impact factor: 8.005
Authors: Janneke Ravensbergen; Smitha Pillai; Dalvin D Méndez-Hernández; Raoul N Frese; Rienk van Grondelle; Devens Gust; Thomas A Moore; Ana L Moore; John T M Kennis Journal: ACS Phys Chem Au Date: 2021-10-14