scholarly journals A new function for the xanthophyll zeaxanthin: glueing chlorophyll biosynthesis to thylakoid protein assembly

2021 ◽  
Vol 478 (1) ◽  
pp. 61-62
Author(s):  
Roberto Bassi
Keyword(s):  
Binding Proteins ◽  
Chlorophyll Biosynthesis ◽  
Protein Assembly ◽  
Light Energy ◽  
Photooxidative Stress ◽  
Photosynthetic Membrane ◽  
Absorption Of Light ◽  
Thylakoid Protein ◽  
Protein Components

Xanthophylls are coloured isoprenoid metabolites synthesized in many organisms with a variety of functions from the attraction of animals for impollination to absorption of light energy for photosynthesis to photoprotection against photooxidative stress. The finding by Proctor and co-workers makes a new addition to the last type of functions by showing that zeaxanthin is instrumental in coordinating chlorophyll biosynthesis with the insertion of pigment-binding proteins into the photosynthetic membrane by glueing the protein components catalyzing these functions into a supercomplex and regulating its activity.

scholarly journals Heparin- and Zn2+-binding proteins from boar seminal plasma.

1999 ◽  
Vol 46 (4) ◽  
pp. 935-939 ◽  
Author(s):  
D Hołody ◽  
J Strzezek
Keyword(s):  
Amino Acid ◽  
Affinity Chromatography ◽  
Molecular Mass ◽  
Seminal Plasma ◽  
Binding Proteins ◽  
Reproductive Tract ◽  
Female Reproductive Tract ◽  
Heparin Binding ◽  
Sds Page ◽  
Protein Components

Low molecular mass, heparin-binding proteins from seminal plasma play an important role in gametes interaction whereas plasmatic Zn2+-binding proteins stabilize chromatin and plasmalemma structures and protect spermatozoa in the female reproductive tract. By means of affinity chromatography the heparin- and Zn2+-binding proteins were isolated from boar seminal plasma and both preparations were analyzed by reverse HPLC. Most of the proteins bound to heparine and Zn2+-ions were classified as spermadhesins. Three fractions binding exclusively Zn2+ were isolated. They differ in amino-acid composition, content of glucosamine and content of protein components revealed by SDS/PAGE.

Influence of Norflurazon on the Activation of Substituted Diphenylether Herbicides by Light

Weed Science ◽  
1983 ◽  
Vol 31 (1) ◽  
pp. 109-112 ◽  
Author(s):  
Robert M. Devlin ◽  
Stanislaw J. Karczmarczyk ◽  
Irena I. Zbiec
Keyword(s):  
Zea Mays ◽  
Light Energy ◽  
Absorption Of Light

Oxyfluorfen [2 - chloro -1 - (3 - ethoxy - 4 - nitrophenoxy) -4 - (trifluoromethyl)benzene] and RH-8817 {ethyl 5 - [2-chloro - 4 -{trifluoromethyl) phenoxy] - 2 - nitrobenzoate} require light for activation. Removal of carotenoids by treating corn (Zea maysL.) seedlings with norflurazon [4 - chloro - 5 - (methylamino) - 2 - (α, α, α - trifluoro -m- tolyl) - 3 (2H) - pyridazinone] rendered them partially tolerant of oxyfluorfen and RH-8817 even when grown in the light. The activation of substituted diphenylether herbicides may occur as a result of the absorption of light energy by carotenoids.

scholarly journals Photocatalytic plant LPOR forms helical lattices that shape membranes for chlorophyll synthesis

2020 ◽  
Author(s):  
Henry C. Nguyen ◽  
Arthur A. Melo ◽  
Jerzy Kruk ◽  
Adam Frost ◽  
Michal Gabruk
Keyword(s):  
Reaction Mechanisms ◽  
Spectral Properties ◽  
Chlorophyll Biosynthesis ◽  
3D Structure ◽  
Chlorophyll Synthesis ◽  
Protochlorophyllide Oxidoreductase ◽  
Photosynthetic Membrane ◽  
Life On Earth ◽  
Outer Membrane Leaflet ◽  
Chl Biosynthesis

AbstractChlorophyll (Chl) biosynthesis, crucial to life on Earth, is tightly regulated because its precursors are phototoxic1. In flowering plants, the enzyme Light-dependent Protochlorophyllide OxidoReductase (LPOR) captures photons to catalyze the penultimate reaction: the reduction of a double-bond within protochlorophyllide (Pchlide) to generate chlorophyllide (Chlide)2,3. In darkness, LPOR oligomerizes to facilitate photon energy transfer and catalysis4,5. However, the complete 3D structure of LPOR, the higher-order architecture of LPOR oligomers, and the implications of these self-assembled states for catalysis, including how LPOR positions Pchlide and the cofactor NADPH, remain unknown. Here we report the atomic structure of LPOR assemblies by electron cryo-microscopy (cryoEM). LPOR polymerizes with its substrates into helical filaments around constricted lipid bilayer tubes. Portions of LPOR and Pchlide insert into the outer membrane leaflet, targeting the product, Chlide, to the membrane for the final reaction site of chlorophyll biosynthesis. In addition to its crucial photocatalytic role, we show that in darkness LPOR filaments directly shape membranes into high-curvature tubules with the spectral properties of the prolammelar body, whose light-triggered disassembly provides lipids for thylakoid assembly. Our structure of the catalytic site, moreover, challenges previously proposed reaction mechanisms6. Together, our results reveal a new and unexpected synergy between photosynthetic membrane biogenesis and chlorophyll synthesis in plants orchestrated by LPOR.

scholarly journals Reconstitution and AFM Observation of Photosynthetic Membrane Protein Assembly in Planar Lipid Bilayers

2011 ◽  
Vol 9 ◽  
pp. 15-20 ◽  
Author(s):  
Ayumi Sumino ◽  
Takehisa Dewa ◽  
Nobuaki Sasaki ◽  
Natsuko Watanabe ◽  
Masaharu Kondo ◽  
...  
Keyword(s):  
Membrane Protein ◽  
Lipid Bilayers ◽  
Protein Assembly ◽  
Planar Lipid Bilayers ◽  
Photosynthetic Membrane ◽  
Afm Observation

scholarly journals Nuclear RNP complex assembly initiates cytoplasmic RNA localization

2004 ◽  
Vol 165 (2) ◽  
pp. 203-211 ◽  
Author(s):  
Tracy L. Kress ◽  
Young J. Yoon ◽  
Kimberly L. Mowry
Keyword(s):  
Protein Interactions ◽  
Binding Proteins ◽  
Rna Binding ◽  
Rna Binding Proteins ◽  
Rna Localization ◽  
Rna Sequences ◽  
Cytoplasmic Rna ◽  
Rnp Complex ◽  
Maternal Mrnas ◽  
Protein Components

Cytoplasmic localization of mRNAs is a widespread mechanism for generating cell polarity and can provide the basis for patterning during embryonic development. A prominent example of this is localization of maternal mRNAs in Xenopus oocytes, a process requiring recognition of essential RNA sequences by protein components of the localization machinery. However, it is not yet clear how and when such protein factors associate with localized RNAs to carry out RNA transport. To trace the RNA–protein interactions that mediate RNA localization, we analyzed RNP complexes from the nucleus and cytoplasm. We find that an early step in the localization pathway is recognition of localized RNAs by specific RNA-binding proteins in the nucleus. After transport into the cytoplasm, the RNP complex is remodeled and additional transport factors are recruited. These results suggest that cytoplasmic RNA localization initiates in the nucleus and that binding of specific RNA-binding proteins in the nucleus may act to target RNAs to their appropriate destinations in the cytoplasm.

Primary photochemical reactions in chloroplast photosynthesis

1974 ◽  
Vol 7 (2) ◽  
pp. 131-177 ◽  
Author(s):  
Alan J. Bearden ◽  
Richard Malkin
Keyword(s):  
Reduction Reaction ◽  
Photochemical Reactions ◽  
Light Energy ◽  
Pigment Molecule ◽  
Oxidation Reduction ◽  
Absorption Of Light ◽  
Oxidation Reduction Reaction ◽  
Chemical Products ◽  
Identification And Characterization

Photosynthesis begins with the absorption of light energy and this absorbed energy is transferred to special sites, termed reaction centres. At these sites, the light energy is transformed into chemical products through an oxidation-reduction reaction that generates the primary reactants, an oxidized pigment molecule (P+) and a reduced electron acceptor (A–) (Clayton, 1972). The subsequent reactions of these species in the dark ultimately results in the formation of chemical products required for the fixation of CO2. In this essay we will discuss the nature of the primary reactants generated in the light reactions of chloroplast photosynthesis, stressing recent advances in the identification and characterization of such reactants.

Intelligent Detector Research and Development of Water Quality Based on Lon Bus

2014 ◽  
Vol 530-531 ◽  
pp. 204-208
Author(s):  
Jian Huan Su ◽  
Yin Jun Zhang
Keyword(s):  
Water Pollution ◽  
Water Quality ◽  
Research And Development ◽  
Light Energy ◽  
Spectral Absorption ◽  
Main Processor ◽  
Characteristic Absorption ◽  
Absorption Of Light ◽  
Quality Testing ◽  
Absorption Characteristics

Present our water pollution has become a prominent issue, in order to further enhance the water quality testing and management, so the paper designed the system has easy to carry and test simplify, etc. because of the system using neuron 3150 chip as the main processor, the circuit is easy to design. The system is according to water quality, dolor reactants which are chosen according to the measured parameters have different spectral absorption characteristics. At the characteristic absorption wavelength, the absorption of light energy depends on the content of the measured ingredients.

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