scholarly journals Expanding Covalent Attachment Sites of Nonnative Chromophores to Encompass the C-Terminal Hydrophilic Domain in Biohybrid Light-Harvesting Architectures

ChemPhotoChem ◽  
2018 ◽  
Vol 2 (3) ◽  
pp. 300-313 ◽  
Author(s):  
Don Hood ◽  
Tuba Sahin ◽  
Pamela S. Parkes-Loach ◽  
Jieying Jiao ◽  
Michelle A. Harris ◽  
...  
Keyword(s):  
Light Harvesting ◽  
Covalent Attachment ◽  
Attachment Sites ◽  
Hydrophilic Domain

scholarly journals Interplay between differentially expressed enzymes contributes to light color acclimation in marineSynechococcus

2019 ◽  
Vol 116 (13) ◽  
pp. 6457-6462 ◽  
Author(s):  
Joseph E. Sanfilippo ◽  
Adam A. Nguyen ◽  
Laurence Garczarek ◽  
Jonathan A. Karty ◽  
Suman Pokhrel ◽  
...  
Keyword(s):  
Blue Light ◽  
Light Harvesting ◽  
Green Light ◽  
Cysteine Residue ◽  
Covalent Attachment ◽  
Critical Feature ◽  
Light Harvesting Complexes ◽  
Important Group ◽  
Chromatic Acclimation ◽  
Light Color

MarineSynechococcus, a globally important group of cyanobacteria, thrives in various light niches in part due to its varied photosynthetic light-harvesting pigments. ManySynechococcusstrains use a process known as chromatic acclimation to optimize the ratio of two chromophores, green-light–absorbing phycoerythrobilin (PEB) and blue-light–absorbing phycourobilin (PUB), within their light-harvesting complexes. A full mechanistic understanding of howSynechococcuscells tune their PEB to PUB ratio during chromatic acclimation has not yet been obtained. Here, we show that interplay between two enzymes named MpeY and MpeZ controls differential PEB and PUB covalent attachment to the same cysteine residue. MpeY attaches PEB to the light-harvesting protein MpeA in green light, while MpeZ attaches PUB to MpeA in blue light. We demonstrate that the ratio ofmpeYtompeZmRNA determines if PEB or PUB is attached. Additionally, strains encoding only MpeY or MpeZ do not acclimate. Examination of strains ofSynechococcusisolated from across the globe indicates that the interplay between MpeY and MpeZ uncovered here is a critical feature of chromatic acclimation for marineSynechococcusworldwide.

scholarly journals Inter-ligand energy transfer in dye chromophores attached to high bandgap SiO2 nanoparticles

2019 ◽  
Vol 55 (60) ◽  
pp. 8804-8807 ◽  
Author(s):  
Michael B. Price ◽  
Andrew Paton ◽  
Jeffrey Gorman ◽  
Isabella Wagner ◽  
Geoffry Laufersky ◽  
...  
Keyword(s):  
Energy Transfer ◽  
Silicon Dioxide ◽  
Light Harvesting ◽  
Sio2 Nanoparticles ◽  
Covalent Attachment ◽  
Artificial Light ◽  
Silicon Dioxide Nanoparticles ◽  
Organic Chromophores

Simple artificial light harvesting networks can be created by the covalent attachment of organic chromophores to silicon dioxide nanoparticles.

scholarly journals Exchange of a single amino acid residue in the cryptophyte phycobiliprotein lyase GtCPES expands its substrate specificity

2020 ◽  
Author(s):  
Natascha Tomazic ◽  
Kristina E. Overkamp ◽  
Marco Aras ◽  
Antonio J. Pierik ◽  
Eckhard Hofmann ◽  
...  
Keyword(s):  
Amino Acid ◽  
Substrate Specificity ◽  
Amino Acid Residue ◽  
Light Harvesting ◽  
Functional Characterization ◽  
Binding Pocket ◽  
Covalent Attachment ◽  
Single Amino Acid ◽  
Oxygenic Photosynthesis ◽  
Single Amino Acid Residue

ABSTRACTCryptophyte algae are among the few eukaryotes that employ phycobiliproteins (PBP) for light harvesting during oxygenic photosynthesis. In contrast to the cyanobacterial PBP that are organized in large membrane-associated super complexes, the phycobilisomes, those from cryptophytes are soluble within the chloroplast thylakoid lumen. Their light-harvesting capacity is due to covalent linkage of several open-chain tetrapyrrole chromophores (phycobilins). Guillardia theta utilizes the PBP phycoerythrin PE545 with 15,16-dihydrobiliverdin (DHBV) in addition to phycoerythrobilin (PEB) as chromophores. Thus far, the assembly of cryptophyte PBPs is not yet completely understood but involves the action of PBP-lyases as shown for cyanobacterial PBP. PBP-lyases facilitate the attachment of the chromophore in the right configuration and stereochemistry. Here we present the functional characterization of eukaryotic S-type PBP lyase GtCPES from G. theta. We show GtCPES mediated transfer and covalent attachment of PEB to the conserved Cys82 of the acceptor PBP β-subunit (PmCpeB) of Prochlorococcus marinus MED4. Based on the previously solved crystal structure, the GtCPES binding pocket was investigated using site-directed mutagenesis. Thereby, amino acid residues involved in phycobilin binding and transfer were identified. Interestingly, exchange of a single amino acid residue Met67 to Ala extended the substrate specificity to phycocyanobilin (PCB) likely by enlarging the substrate-binding pocket. Variant GtCPES_M67A binds both PEB and PCB forming a stable, colorful complex in vitro and in vivo produced in Escherichia coli. GtCPES_M67A is able to mediate PCB transfer to Cys82 of PmCpeB. Based on our data we postulate that a single amino acid residue determines the bilin-specificity of phycoerythrin S-type lyases but that additional factors regulate hand over to the target protein.

Identification by MALDI-TOF Mass Spectrometry of 17α-Bromoacetamidopropylestradiol Covalent Attachment Sites on Estrogen Receptor α†

Biochemistry ◽  
2002 ◽  
Vol 41 (52) ◽  
pp. 15713-15727 ◽  
Author(s):  
Hélène Mattras ◽  
Sigrid Aliau ◽  
Eric Richard ◽  
Jean-Claude Bonnafous ◽  
Patrick Jouin ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Estrogen Receptor ◽  
Estrogen Receptor Α ◽  
Covalent Attachment ◽  
Maldi Tof Mass Spectrometry ◽  
Maldi Tof ◽  
Attachment Sites

High-Resolution electron crystallography of the light-harvesting chlorophyll-a/b protein complex from chloroplast membranes

1990 ◽  
Vol 48 (1) ◽  
pp. 610-610
Author(s):  
Werner Kühlbrandt ◽  
Da Neng Wang ◽  
K.H. Downing
Keyword(s):  
High Resolution ◽  
Electron Diffraction ◽  
Chlorophyll A ◽  
Protein Complex ◽  
Structural Integrity ◽  
Light Harvesting ◽  
Lhc Ii ◽  
Diffraction Patterns ◽  
Difference Fourier ◽  
2D Crystals

The light-harvesting chlorophyll-a/b protein complex (LHC-II) is the most abundant membrane protein in the chloroplasts of green plants where it functions as a molecular antenna of solar energy for photosynthesis. We have grown two-dimensional (2d) crystals of the purified, detergent-solubilized LHC-II . The crystals which measured 5 to 10 μm in diameter were stabilized for electron microscopy by washing with a 0.5% solution of tannin. Electron diffraction patterns of untilted 2d crystals cooled to 130 K showed sharp spots to 3.1 Å resolution. Spot-scan images of 2d crystals were recorded at 160 K with the Berkeley microscope . Images of untilted crystals were processed, using the unbending procedure by Henderson et al . A projection map of the complex at 3.7Å resolution was generated from electron diffraction amplitudes and high-resolution phases obtained by image processing .A difference Fourier analysis with the same image phases and electron diffraction amplitudes recorded of frozen, hydrated specimens showed no significant differences in the 3.7Å projection map. Our tannin treatment therefore does not affect the structural integrity of the complex.

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.

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