دانلود رایگان مقاله لاتین غشا تیلاکوئید فتوسنتزی از سایت الزویر
عنوان فارسی مقاله:
پویایی پروتئین و چربی در غشاء تیلاکوئید فتوسنتزی مورد بررسی در محل حالت جامد NMR
عنوان انگلیسی مقاله:
Protein and lipid dynamics in photosynthetic thylakoid membranes investigated by in-situ solid-state NMR
سال انتشار : 2016
برای دانلود رایگان مقاله غشا تیلاکوئید فتوسنتزی اینجا کلیک نمایید.
مقدمه انگلیسی مقاله:
1. Introduction
Conversion of sunlight into chemical energy takes place inside photosynthetic membranes, where pigment-protein nano-machines carry out a cascade of reactions that evolve in time and space [1]. In order to safely perform the photosynthesis reactions and ensure organism fitness under fluctuating light conditions, constant membrane remodeling takes place. In excess light, feedback deregulation mechanisms induce quenching of sunlight excitations, dissipating the excess light energy as heat and creating a safety valve for the photosynthetic apparatus [2, 3]. In plant and algae thylakoids, photosynthesis is regulated through complex interplay between molecular conformational changes, reversible supramolecular interactions and membrane phase transitions [4]. Thylakoids are densely packed with proteins that occupy ~70% of the membrane space and control the membrane phases [5]. Short- and longterm acclimation of thylakoids to light and cold stress involves reorganization of antenna-supercomplexes [4,6–9], conversion of the xanthophyll violaxanthin (Vio) into zeaxanthin (Zea) via the xanthophyll cycle [1] and increase of lipid unsaturation by changing lipid composition [10]. Modulated by low pH, phosphorylation and the xanthophyll cycle, a part of the light-harvesting complex II (LHCII) antenna population disconnects from the Photosystem II (PSII) complexes and self-aggregates to form chlorophyll (Chl)-quenched states, which dissipate excess light [11]. The effects of xanthophyll composition on regulation and photoprotection in thylakoids have been investigated in various studies. Zea is known to play a central role in photoprotection, through its participation in Non-Photochemical Quenching (NPQ) [12] but also by preventing lipid oxidative damage in the membrane [13]. The antioxidant activity of xanthophyll pigments present in membranes was indeed found to be related to their physical-chemical interaction with lipids [14] and their presence was shown to increase the penetration barrier to molecular oxygen [15]. Moreover, several in vivo and in-vitro studies have reported increased rigidity of Zea-containing membranes [13,16], contributing to their stabilization. The precise role of Zea in NPQ is still under debate. The green microalga Chlamydomonas reinhardtii(Cr.) npq2 mutant is defective in Zea epoxidase and has an impaired xanthophyll cycle. In npq2 lutein and β-carotene are the major carotenoids while it is unable to synthetize antheraxanthin and violaxanthin and accumulates Zea constitutively, under all light conditions. The mutation does not impair the photoautotrophic growth of npq2 with respect to the parental strain (cw15) in various growing conditions. Npq2 mutant only showed a decrease in chlorophyll content per cell upon cultivation in high light with a consequent increase in the carotenoid/Chl ratio. Npq2 mutant showed a decreased quantum yield of PSII (Fv/Fm) [17] but also faster fluorescence quenching upon actinic-light exposure [18,19]. Zea has been suggested to be involved in quenching of excess energy by multiple mechanisms, by activating a quenched state in LHC protein complexes upon binding [20–22] but also at the membrane level, mediating interactions between the complexes [23]. The accumulation of Zea was also demonstrated to protect the polyunsatured lipids, during photooxidative stress, as well as α-tocopherol [13], showing a strong antioxidative effect from Zea independent from its binding to PSII light-harvesting complexes. In this work, we explored the use of in-situ 13C solid-state Nuclear Magnetic Resonance (NMR) on whole thylakoids to gain insight in protein and lipid conformational dynamics and the effect of Zea accumulation. 13C-NMR spectroscopy in conjunction with biosynthetic uniformly 13C isotope labeling provides us with a unique method to simultaneously detect protein, lipid and xanthophyll molecular constituents and measure their molecular dynamics directly. We analyzed Cr. thylakoids from wild type (cw15) and from npq2 mutant that, as already mentioned accumulates Zea in the thylakoids. 13C Magic Angle Spinning (MAS) NMR spectra were obtained by direct and cross polarization to separate and quantify rigid and dynamic membrane molecular components. To measure the temperature-dependent dynamical properties, spectra were collected over a temperature range from 0 to 25 °C. In addition, T1ρ relaxation experiments were performed to further analyze protein backbone molecular dynamics. Results show differential dynamics of proteins, lipids and xanthophylls in cw15 and npq2 membranes. The npq2 membranes contain more xanthophylls and orderedphase lipids with reduced dynamics, as well as mobile-phase lipids with enlarged dynamics, spanning a broader dynamical range. Our study validates the application of 13C solid-state NMR spectroscopy for functional screening of molecular membrane characteristics and demonstrates how Zea accumulation influences the conformational dynamics of protein and lipid constituents, affecting the functionality of heterogeneous thylakoid membranes.
برای دانلود رایگان مقاله غشا تیلاکوئید فتوسنتزی اینجا کلیک نمایید.
کلمات کلیدی:
PDF]Protein and lipid dynamics in photosynthetic thylakoid membranes ... iranarze.ir/wp-content/uploads/2016/10/E2250.pdf Sep 11, 2016 - investigated by in-situ solid-state NMR ... Photosynthetic thylakoid membranes contain the protein machinery to convert sunlight in chemical ... Protein and lipid dynamics in photosynthetic thylakoid membranes ... lic.leidenuniv.nl/publications/5363 Title, Protein and lipid dynamics in photosynthetic thylakoid membranes investigated by in-situ solid-state NMR. Publication Type, Journal Article. [PDF]in situ probed solid-state NMR on photosynthetic thylakoid membranes program.euromar2016.org/abstracts/338.pdf in situ probed solid-state NMR on photosynthetic thylakoid membranes ... 1Dept. of solid-state NMR, Leiden Institute of Chemistry, Einsteinweg 55, 2333 ... abundant in the thylakoid membranes, which may open possibilities to investigate their ... Protein and lipid dynamics in photosynthetic thylakoid membranes ... www.nat.vu.nl/~ivo/LH2016Egmond/AzadiChegeni.html 1Leiden Institute of Chemistry, Solid State NMR, Leiden, Netherlands ... thylakoid membranes to gain insight in protein and lipid molecular dynamics in situ. Protein and lipid dynamics in photosynthetic thylakoid membranes ... www.bionmr.com › BioNMR › Educational resources › Journal club Sep 22, 2016 - 9 posts - 1 author Protein and lipid dynamics in photosynthetic thylakoid membranes investigated by in-situ solid-state NMR Publication date: December 2016 ... Biochimica et biophysica acta. Bioenergetics - Terkko Navigator https://www.terkko.helsinki.fi/.../15523384_protein-and-lipid-dyna... Translate this page Protein and lipid dynamics in photosynthetic thylakoid membranes investigated by in-situ solid-state NMR. Added 144 days ago (15.10.2016). Journal: ... Protein and lipid dynamics in photosynthetic thylakoid membranes ... www.bioportfolio.com › Topics › Nutrition › Research Sep 11, 2016 - Photosynthetic thylakoid membranes contain the protein machinery to convert ... thylakoid membranes investigated by in-situ solid-state NMR. Protein and lipid dynamics in photosynthetic thylakoid membranes ... lightharvesting2016.nl/.../protein-and-lipid-dynamics-photosynthetic-thylakoid-mem... Protein and lipid dynamics in photosynthetic thylakoid membranes probed by in-situ solid-state NMR. F. Azadi Chegenia, K.B. Sai Sankar Guptaa, G. Perinb, ...
