scholarly journals Metabolic regulation of photosynthetic membrane structure tunes electron transfer function

2018 ◽  
Vol 475 (7) ◽  
pp. 1225-1233 ◽  
Author(s):  
Matthew P. Johnson
Keyword(s):  
Electron Transfer ◽  
Metabolic Regulation ◽  
Higher Plants ◽  
Three Dimensional ◽  
Feedback Regulation ◽  
Membrane Dynamics ◽  
Dimensional Structure ◽  
Photosynthetic Membrane ◽  
Light Harvesting Complex ◽  
Light Harvesting Complex Ii

The photosynthetic chloroplast thylakoid membrane of higher plants is a complex three-dimensional structure that is morphologically dynamic on a timescale of just a few minutes. The membrane dynamics are driven by the phosphorylation of light-harvesting complex II (LHCII) by the STN7 kinase, which controls the size of the stacked grana region relative to the unstacked stromal lamellae region. Here, I hypothesise that the functional significance of these membrane dynamics is in controlling the partition of electrons between photosynthetic linear and cyclic electron transfer (LET and CET), which determines the ratio of NADPH/ATP produced. The STN7 kinase responds to the metabolic state of the chloroplast by sensing the stromal redox state. A high NADPH/ATP ratio leads to reduction of thioredoxin f (TRXf), which reduces a CxxxC motif in the stromal domain of STN7 leading to its inactivation, whereas a low NADPH/ATP ratio leads to oxidation of TRXf and STN7 activation. Phosphorylation of LHCII leads to smaller grana, which favour LET by speeding up diffusion of electron carriers plastoquinone (PQ) and plastocyanin (PC) between the domains. In contrast, dephosphorylation of LHCII leads to larger grana that slow the diffusion of PQ and PC, leaving the PQ pool in the stroma more oxidised, thus enhancing the efficiency of CET. The feedback regulation of electron transfer by the downstream metabolism is crucial to plant fitness, since perturbations in the NADPH/ATP ratio can rapidly lead to the inhibition of photosynthesis and photo-oxidative stress.

scholarly journals Phosphorylation Controls the Three-dimensional Structure of Plant Light Harvesting Complex II

1997 ◽  
Vol 272 (29) ◽  
pp. 18350-18357 ◽  
Author(s):  
Anders Nilsson ◽  
Dalibor Stys ◽  
Torbjörn Drakenberg ◽  
Michael D. Spangfort ◽  
Sture Forsén ◽  
...  
Keyword(s):  
Light Harvesting ◽  
Three Dimensional ◽  
Dimensional Structure ◽  
Light Harvesting Complex ◽  
Complex Ii ◽  
Three Dimensional Structure ◽  
Light Harvesting Complex Ii

Macroorganisation and flexibility of thylakoid membranes

2019 ◽  
Vol 476 (20) ◽  
pp. 2981-3018 ◽  
Author(s):  
Petar H. Lambrev ◽  
Parveen Akhtar
Keyword(s):  
Light Harvesting ◽  
Current Knowledge ◽  
Three Dimensional ◽  
Photosynthetic Apparatus ◽  
Dynamic Responses ◽  
State Transitions ◽  
Photochemical Quenching ◽  
Light Harvesting Complex ◽  
Complex Ii ◽  
Light Harvesting Complex Ii

Abstract The light reactions of photosynthesis are hosted and regulated by the chloroplast thylakoid membrane (TM) — the central structural component of the photosynthetic apparatus of plants and algae. The two-dimensional and three-dimensional arrangement of the lipid–protein assemblies, aka macroorganisation, and its dynamic responses to the fluctuating physiological environment, aka flexibility, are the subject of this review. An emphasis is given on the information obtainable by spectroscopic approaches, especially circular dichroism (CD). We briefly summarise the current knowledge of the composition and three-dimensional architecture of the granal TMs in plants and the supramolecular organisation of Photosystem II and light-harvesting complex II therein. We next acquaint the non-specialist reader with the fundamentals of CD spectroscopy, recent advances such as anisotropic CD, and applications for studying the structure and macroorganisation of photosynthetic complexes and membranes. Special attention is given to the structural and functional flexibility of light-harvesting complex II in vitro as revealed by CD and fluorescence spectroscopy. We give an account of the dynamic changes in membrane macroorganisation associated with the light-adaptation of the photosynthetic apparatus and the regulation of the excitation energy flow by state transitions and non-photochemical quenching.

scholarly journals Cryo-Electron Tomography Reveals the Comparative Three-Dimensional Architecture of Prochlorococcus, a Globally Important Marine Cyanobacterium

2007 ◽  
Vol 189 (12) ◽  
pp. 4485-4493 ◽  
Author(s):  
Claire S. Ting ◽  
Chyongere Hsieh ◽  
Sesh Sundararaman ◽  
Carmen Mannella ◽  
Michael Marko
Keyword(s):  
Cell Wall ◽  
Electron Tomography ◽  
Three Dimensional ◽  
Membrane System ◽  
Niche Differentiation ◽  
Dimensional Structure ◽  
Comparative Genomic ◽  
Photosynthetic Membrane ◽  
Peptidoglycan Biosynthesis ◽  
Cryo Electron Tomography

ABSTRACT In an age of comparative microbial genomics, knowledge of the near-native architecture of microorganisms is essential for achieving an integrative understanding of physiology and function. We characterized and compared the three-dimensional architecture of the ecologically important cyanobacterium Prochlorococcus in a near-native state using cryo-electron tomography and found that closely related strains have diverged substantially in cellular organization and structure. By visualizing native, hydrated structures within cells, we discovered that the MED4 strain, which possesses one of the smallest genomes (1.66 Mbp) of any known photosynthetic organism, has evolved a comparatively streamlined cellular architecture. This strain possesses a smaller cell volume, an attenuated cell wall, and less extensive intracytoplasmic (photosynthetic) membrane system compared to the more deeply branched MIT9313 strain. Comparative genomic analyses indicate that differences have evolved in key structural genes, including those encoding enzymes involved in cell wall peptidoglycan biosynthesis. Although both strains possess carboxysomes that are polygonal and cluster in the central cytoplasm, the carboxysomes of MED4 are smaller. A streamlined cellular structure could be advantageous to microorganisms thriving in the low-nutrient conditions characteristic of large regions of the open ocean and thus have consequences for ecological niche differentiation. Through cryo-electron tomography we visualized, for the first time, the three-dimensional structure of the extensive network of photosynthetic lamellae within Prochlorococcus and the potential pathways for intracellular and intermembrane movement of molecules. Comparative information on the near-native structure of microorganisms is an important and necessary component of exploring microbial diversity and understanding its consequences for function and ecology.

Role of LHCII-containing macrodomains in the structure, function and dynamics of grana

2000 ◽  
Vol 27 (3) ◽  
pp. 279 ◽  
Author(s):  
G. Garab ◽  
L. Mustárdy
Keyword(s):  
Excitation Energy ◽  
Long Range ◽  
Structural Changes ◽  
Higher Plants ◽  
Three Dimensional ◽  
Dimensional Structure ◽  
Lateral Heterogeneity ◽  
Long Distance ◽  
3D Network

In higher plants and green algae two types of thylakoids are distinguished, granum (stacked) and stroma (unstacked) thylakoids. They form a three-dimensional (3D) network with large lateral heterogeneity: photosystem II (PSII) and the associated main chlorophyll a/b light-harvesting complex (LHCII) are found predominantly in the stacked region, while PSI and LHCI are located mainly in the unstacked region of the membrane. This picture emerged from the discovery of the physical separation of the two photosystems (Boardman and Anderson 1964). Granal chloroplasts possess significant flexibility, which is essential for optimizing the photosynthetic machinery under various environmental conditions. However, our understanding concerning the assembly, structural dynamics and regulatory functions of grana is far from being complete. In this paper we overview the significance of the three-dimensional structure of grana in the absorption properties, ionic equilibrations, and in the diffusion of membrane components between the stacked and unstacked regions. Further, we discuss the role of chiral macrodomains in the grana. Lateral heterogeneity of thylakoid membranes is proposed to be a consequence of the formation of macrodomains constituted of LHCII and PSII; their long range order permits long distance migration of excitation energy, which explains the energetic connectivity of PSII particles. The ability of macrodomains to undergo light-induced reversible structural changes lends structural flexibility to the granum. In purified LHCII, which has also been shown to form stacked lamellar aggregates with long range chiral order, excitation energy migrates for large distances; these macroaggregates are also capable of undergoing light-induced reversible structural changes and fluorescence quenching. Hence, some basic properties of grana appear to originate from its main constituent, the LHCII.

scholarly journals Xanthophylls in Light-Harvesting Complex II of Higher Plants:  Light Harvesting and Triplet Quenching†

Biochemistry ◽  
1997 ◽  
Vol 36 (40) ◽  
pp. 12208-12215 ◽  
Author(s):  
Erwin J. G. Peterman ◽  
Claudiu C. Gradinaru ◽  
Florentine Calkoen ◽  
Jeroen C. Borst ◽  
Rienk van Grondelle ◽  
...  
Keyword(s):  
Light Harvesting ◽  
Higher Plants ◽  
Light Harvesting Complex ◽  
Complex Ii ◽  
Light Harvesting Complex Ii

scholarly journals Chlorophyll a and carotenoid triplet states in light-harvesting complex II of higher plants

1995 ◽  
Vol 69 (6) ◽  
pp. 2670-2678 ◽  
Author(s):  
E.J. Peterman ◽  
F.M. Dukker ◽  
R. van Grondelle ◽  
H. van Amerongen
Keyword(s):  
Chlorophyll A ◽  
Light Harvesting ◽  
Higher Plants ◽  
Triplet States ◽  
Light Harvesting Complex ◽  
Complex Ii ◽  
Light Harvesting Complex Ii

Ultrafast Spectroscopy of Trimeric Light-Harvesting Complex II from Higher Plants

1997 ◽  
Vol 101 (10) ◽  
pp. 1902-1909 ◽  
Author(s):  
J. P. Connelly ◽  
M. G. Müller ◽  
M. Hucke ◽  
G. Gatzen ◽  
C. W. Mullineaux ◽  
...  
Keyword(s):  
Ultrafast Spectroscopy ◽  
Light Harvesting ◽  
Higher Plants ◽  
Light Harvesting Complex ◽  
Complex Ii ◽  
Light Harvesting Complex Ii
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