title: Low-pH induced reversible reorganizations of chloroplast thylakoid membranes - As revealed by small-angle neutron scattering.
abstract: Energization of thylakoid membranes brings about the acidification of the lumenal aqueous phase, which activates important regulatory mechanisms. Earlier Jajoo and coworkers (2014 FEBS Lett. 588:970) have shown that low pH in isolated plant thylakoid membranes induces changes in the excitation energy distribution between the two photosystems. In order to elucidate the structural background of these changes, we used small-angle neutron scattering on thylakoid membranes exposed to low p2H (pD) and show that gradually lowering the p2H from 8.0 to 5.0 causes small but well discernible reversible diminishment of the periodic order and the lamellar repeat distance and an increased mosaicity - similar to the effects elicited by light-induced acidification of the lumen. Our data strongly suggest that thylakoids dynamically respond to the membrane energization and actively participate in different regulatory mechanisms.
authors.affiliation: Wigner Research Centre for Physics, Institute for Solid State Physics and Optics, Hungarian Academy of Sciences, H-1121 Budapest, Hungary; Paul Scherrer Institute, Laboratory for Neutron Scattering and Imaging, 5232 Villigen PSI, Switzerland.
authors.forename: Renáta
authors.initials: R
authors.lastname: Ünnep
authors.affiliation: Institute of Plant Biology, Biological Research Center, Hungarian Academy of Sciences, POB 521, H-6701 Szeged, Hungary.
authors.forename: Ottó
authors.initials: O
authors.lastname: Zsiros
authors.affiliation: College of Nyíregyháza, Institute of Environmental Science, H-4400 Nyíregyháza, Hungary.
authors.forename: Zsolt
authors.initials: Z
authors.lastname: Hörcsik
authors.affiliation: Wigner Research Centre for Physics, Institute for Solid State Physics and Optics, Hungarian Academy of Sciences, H-1121 Budapest, Hungary.
authors.forename: Márton
authors.initials: M
authors.lastname: Markó
authors.affiliation: School of Life Science, Devi Ahilya University, Khandwa Road, Indore 452 001, India.
authors.forename: Anjana
authors.initials: A
authors.lastname: Jajoo
authors.affiliation: Paul Scherrer Institute, Laboratory for Neutron Scattering and Imaging, 5232 Villigen PSI, Switzerland.
authors.forename: Joachim
authors.initials: J
authors.lastname: Kohlbrecher
authors.affiliation: Institute of Plant Biology, Biological Research Center, Hungarian Academy of Sciences, POB 521, H-6701 Szeged, Hungary; Department of Physics, Faculty of Science, Ostrava University, Chittussiho 10, CZ-710 0 Ostrava - Slezská Ostrava, Czech Republic. Electronic address: garab.gyozo@brc.mta.hu.
authors.forename: Győző
authors.initials: G
authors.lastname: Garab
authors.affiliation: Paul Scherrer Institute, Laboratory for Neutron Scattering and Imaging, 5232 Villigen PSI, Switzerland; Wigner Research Centre for Physics, Institute for Solid State Physics and Optics, Hungarian Academy of Sciences, H-1121 Budapest, Hungary. Electronic address: gergely.nagy@psi.ch.
authors.forename: Gergely
authors.initials: G
authors.lastname: Nagy
mesh_terms: D004735:Energy Transfer; D006863:Hydrogen-Ion Concentration; D008560:Membrane Fluidity; D033363:Neutron Diffraction; D018532:Pisum sativum / Q000378:metabolism* / Q000648:ultrastructure; D010788:Photosynthesis; D045331:Photosystem I Protein Complex / Q000378:metabolism* / Q000648:ultrastructure; D045332:Photosystem II Protein Complex / Q000378:metabolism* / Q000648:ultrastructure; D018515:Plant Leaves / Q000378:metabolism; D053838:Scattering, Small Angle; D020524:Thylakoids / Q000378:metabolism* / Q000648:ultrastructure
chemical_list: D045331:Photosystem I Protein Complex; D045332:Photosystem II Protein Complex
keywords: Chloroplast thylakoid membranes; Lamellar repeat distance; Low pH and p(2)H; Small-angle neutron scattering (SANS)