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Marisel R Tuttobene, Pamela Cribb, María Alejandra Mussi
Light modulates global features of the important human pathogen Acinetobacter baumannii lifestyle including metabolism, tolerance to antibiotics and virulence, most of which depend on the short BLUF-type photoreceptor BlsA. In this work, we show that the ability to circumvent iron deficiency is also modulated by light at moderate temperatures, and disclose the mechanism of signal transduction by showing that BlsA antagonizes the functioning of the ferric uptake regulator (Fur) in a temperature-dependent manner...
May 16, 2018: Scientific Reports
Veronika Kottisch, Michael J Supej, Brett P Fors
Gaining temporal control over chain growth is a key challenge in the enhancement of controlled living polymerizations. Though research on photocontrolled polymerizations is still in its infancy, it has already proven useful in the development of previously inaccessible materials. Our research group recently extended photocontrol to cationic polymerizations using 2,4,6-triarylpyrylium salts as photocatalysts. Despite the ability to stop the polymerization for a short amount of time, we observed monomer conversion over long dark periods...
May 11, 2018: Angewandte Chemie
Yvonne Becker, Erik Unger, Manuela A H Fichte, Daniel A Gacek, Andreas Dreuw, Josef Wachtveitl, Peter J Walla, Alexander Heckel
Based on nitrodibenzofuran (NDBF) a new photocage with higher two-photon action cross section and red-shifted absorption was developed. Due to calculations, a dimethylamino functionality (DMA) was added at ring position 7. The uncaging of nucleobases after two-photon excitation (2PE) could be visualized via double-strand displacement in a hydrogel. With this assay we achieved three-dimensional photorelease of DMA-NDBF-protected DNA orthogonal to NDBF-protected strands. While being an excellent 2P-cage, DMA-NDBF is surprisingly stable under visible-light one-photon excitation (1PE)...
March 14, 2018: Chemical Science
Chenxiao Xiong, Lidong Zhang, Meiran Xie, Ruyi Sun
Supramolecular hydrogels that are assembled through dynamic host-guest interactions have presented apparent potential in the construction of materials with promising performance. Herein, a photoregulated hydrogel cross-linked by host-guest interactions with multifunctions of high stretchability, strong toughness, and rapid self-healing property is reported. The hydrogel exhibits unique light-responsive property due to the introduction of two photoisomerized groups. For example, the stress-strain curve of the original hydrogel indicates 1020% rupture strain with the maximum tensile strain value of 214 kPa...
April 20, 2018: Macromolecular Rapid Communications
Anouk S Lubbe, Qing Liu, Sanne J Smith, Jan Willem de Vries, Jos C M Kistemaker, Alex H de Vries, Ignacio Faustino, Zhuojun Meng, Wiktor Szymanski, Andreas Herrmann, Ben L Feringa
Reversible control over the functionality of biological systems via external triggers may be used in future medicine to reduce the need for invasive procedures. Additionally, externally regulated biomacromolecules are now considered as particularly attractive tools in nanoscience and the design of smart materials, due to their highly programmable nature and complex functionality. Incorporation of photoswitches into biomolecules, such as peptides, antibiotics, and nucleic acids, has generated exciting results in the past few years...
April 18, 2018: Journal of the American Chemical Society
Jeremy E B McCallum, Christopher W Coyle, Ryan R Elson, Blake A Titterington
The development of small molecules to stabilize the G-quadruplex structure has garnered significant attention for anticancer drug discovery. Herein, we report the synthesis of several 4,4'-diaminoazobenzene derivatives containing different substituent groups and their ability to bind and stabilize telomeric G-quadruplex DNA. Circular dichroism (CD) spectroscopy was performed to characterize the quadruplex topologies, measure stabilization effects, and evaluate their capabilities for conformational photoregulation...
March 12, 2018: Nucleosides, Nucleotides & Nucleic Acids
Jiali Yang, Changmai Chen, Xinjing Tang
siRNA has been widely applied in research and drug development due to its sequence-specific gene silencing ability. However, how to spatiotemporally control its function is still one of its challenges. Light, a fast and noninvasive trigger, is a promising tool for spatiotemporal control of gene expression. Here, we designed and synthesized a new series of caged siRNAs modified with single cholesterol at the 5' terminal of antisense strand RNA through a photolabile linker (Chol-PL-siRNAs). We demonstrated that these caged siRNAs were successfully used to photochemically regulate both exogenous ( firefly luciferase and gfp) and endogenous gene expression (mitotic kinesin-5, Eg5) in cells...
April 18, 2018: Bioconjugate Chemistry
Liangliang Zhang, Changmai Chen, Xinli Fan, Xinjing Tang
Caged siRNAs incorporating terminal modification were rationally designed for photochemical regulation of gene silencing induced by RNA interference (RNAi). Through the conjugation of a single oligonucleotide aptamer at the 5' terminus of the antisense RNA strand, enhancement of the blocking effect for RNA-induced silencing complex (RISC) formation/processing was expected, due both/either to the aptamers themselves and/or to their interaction with large binding proteins. Two oligonucleotide aptamers (AS1411 and MUC-1) were chosen for aptamer-siRNA conjugation through a photolabile linker...
February 28, 2018: Chembiochem: a European Journal of Chemical Biology
Volker Adam, Deepak K Prusty, Mathias Centola, Marko Škugor, Jeffrey S Hannam, Julián Valero, Bernhard Klöckner, Michael Famulok
Photoregulation is among the most promising tools for development of dynamic DNA nanosystems, due to its high spatiotemporal precision, biocompatibility, and ease of use. So far, azobenzene and its derivatives have shown high potential in photocontrolling DNA duplex hybridization by light-dependent photoisomerization. Despite many recent advances, obtaining sufficiently high photoswitching efficiency under conditions more suitable for work with DNA nanostructures are challenging. Here we introduce a pair of arylazopyrazoles as new photoswitches for efficient and reversible control of DNA hybridization achieved even at room temperature with a low number of required modifications...
January 24, 2018: Chemistry: a European Journal
Niklas Felix König, Sofia Telitel, Salomé Poyer, Laurence Charles, Jean-François Lutz
A photoregulated phosphoramidite iterative process is studied for the synthesis of non-natural, digitally encoded oligo(phosphodiester)s. The oligomers are prepared using two reactive phosphoramidite monomers containing a 2-(2-nitrophenyl)propoxycarbonyl (NPPOC) protected OH group. The stepwise synthesis is performed on an OH-functional soluble polystyrene support, which allows recycling by precipitation in a nonsolvent. Repeating cycles involving phosphoramidite coupling, oxidation of phosphite to phosphate, and NPPOC deprotection by light irradiation at λ = 365 nm are performed in order to prepare oligomers with different lengths and sequences...
December 2017: Macromolecular Rapid Communications
Elena M Willner, Yuu Kamada, Yuki Suzuki, Tomoko Emura, Kumi Hidaka, Hendrik Dietz, Hiroshi Sugiyama, Masayuki Endo
We demonstrate direct observation of the dynamic opening and closing behavior of photocontrollable DNA origami nanoscissors using high-speed atomic force microscopy (HS-AFM). First the conformational change between the open and closed state controlled by adjustment of surrounding salt concentration could be directly observed during AFM scanning. Then light-responsive moieties were incorporated into the nanoscissors to control these structural changes by photoirradiation. Using photoswitchable DNA strands, we created a photoresponsive nanoscissors variant and were able to distinguish between the open and closed conformations after respective irradiation with ultraviolet (UV) and visible (Vis) light by gel electrophoresis and AFM imaging...
October 17, 2017: Angewandte Chemie
Amrita Paul, Rakesh Mengji, Olive Abraham Chandy, Surajit Nandi, Manoranjan Bera, Avijit Jana, Anakuthil Anoop, N D Pradeep Singh
o-Hydroxycinnamate derivatives are well-known phototriggers for fast and direct release of alcohols and amines without proceeding through the cleavage of carbonate or carbamate linkages. Despite these unique features, o-hydroxycinnamates lack extensive applications in biological systems mainly because of their non-fluorescent nature. To overcome this limitation, we have attached a 2-(2'-hydroxyphenyl) benzothiazole (HBT) moiety, capable of rapid excited-state intramolecular proton transfer (ESIPT) to the o-hydroxycinnamate group...
October 18, 2017: Organic & Biomolecular Chemistry
Andrea Bernardi, Andreas Nikolaou, Andrea Meneghesso, Benoît Chachuat, Tomas Morosinotto, Fabrizio Bezzo
The development of mathematical models capable of accurate predictions of the photosynthetic productivity of microalgae under variable light conditions is paramount to the development of large-scale production systems. The process of photoacclimation is particularly important in outdoor cultivation systems, whereby seasonal variation of the light irradiance can greatly influence microalgae growth. This paper presents a dynamic model that captures the effect of photoacclimation on the photosynthetic production...
August 12, 2017: Journal of Biotechnology
Dan Zhao, Xiaoqing Yi, Gongdao Yuan, Renxi Zhuo, Feng Li
A smart targeting drug delivery nanocarrier is successfully constructed based on phototriggered competition of host-guest interaction. The targeting motif, i.e., biotin is first concealed by β-cyclodextrin (β-CD) via host-guest interaction. When the nanoparticles are exposed to UV light, the cleavage of photosensitive groups results in the exposure of adamantane (Ad) groups initially located in the interior of nanoassemblies, and β-CDs capped on biotin ligands can be replaced by Ad because of the higher binding constant between Ad and β-CD than that between biotin and β-CD...
September 2017: Macromolecular Bioscience
Ji Luo, Jessica Torres-Kolbus, Jihe Liu, Alexander Deiters
We genetically encoded three new caged tyrosine analogues with improved photochemical properties by using an engineered pyrrolysyl-tRNA synthetase/tRNACUA pair in bacterial and mammalian cells. We applied the new tyrosine analogues to the photoregulation of firefly luciferase by caging its key tyrosine residue, Tyr340, and observed excellent off-to-on light switching. This reporter was then used to evaluate the activation rates of the different light-removable protecting groups in live cells. We identified the nitropiperonyl caging group as an excellent compromise between incorporation efficiency and photoactivation properties...
July 18, 2017: Chembiochem: a European Journal of Chemical Biology
Alberto Martinez-Cuezva, Adrian Saura-Sanmartin, Tomas Nicolas-Garcia, Cristian Navarro, Raul-Angel Orenes, Mateo Alajarin, Jose Berna
En route to a photoswitchable interlocked catalyst we have proved the ability of thiodiglycolamide to act as a template in the formation of hydrogen-bonded [2]rotaxanes. X-ray diffraction studies reveal the shielding of the sulfide atom by the macrocycle. A series of molecular shuttles are described as having an isomerizable fumaramide and thiodiglycolamide binding sites for controlling the relative ring position at will. By employing these systems as photoregulated catalysts, the TiCl4-mediated chalcogeno-Morita-Baylis-Hillman reaction is tested...
May 1, 2017: Chemical Science
Faming Wang, Enguo Ju, Yijia Guan, Jinsong Ren, Xiaogang Qu
Nanozymes have shown great potential in bioapplications owing to their low cost, high stability, multiple activity, and biocompatibility. However, most of the known nanozymes are always at turn-on state, hindering their further applications. Herein, a simple and versatile method for constructing activity-controllable nanozymes is presented. To the best of our knowledge, this is the first report to utilize the light-driven isomerization of azobenzene (Azo) and host-guest interaction to reversibly photoregulating the activity of nanozyme...
May 16, 2017: Small
Inés Abatedaga, Lorena Valle, Adrián E Golic, Gabriela L Müller, Matías Cabruja, Faustino E Morán Vieyra, Paula C Jaime, María Alejandra Mussi, Claudio D Borsarelli
BlsA is a BLUF photoreceptor present in Acinetobacter baumannii, responsible for modulation of motility, biofilm formation and virulence by light. In this work, we have combined physiological and biophysical evidences to begin to understand the basis of the differential photoregulation observed as a function of temperature. Indeed, we show that blsA expression is reduced at 37°C, which correlates with negligible photoreceptor levels in the cells, likely accounting for absence of photoregulation at this temperature...
May 2017: Photochemistry and Photobiology
Keiji Fushimi, Gen Enomoto, Masahiko Ikeuchi, Rei Narikawa
Cyanobacteriochromes (CBCRs) are photoreceptors that bind to a linear tetrapyrrole within a conserved cGMP-phosphodiesterase/adenylate cyclase/FhlA (GAF) domain and exhibit reversible photoconversion. Red/green-type CBCR GAF domains that photoconvert between red- (Pr) and green-absorbing (Pg) forms occur widely in various cyanobacteria. A putative phototaxis regulator, AnPixJ, contains multiple red/green-type CBCR GAF domains. We previously reported that AnPixJ's second domain (AnPixJg2) but not its fourth domain (AnPixJg4) shows red/green reversible photoconversion...
May 2017: Photochemistry and Photobiology
Steven D Schwartzbach
Euglena can use light and CO2, photosynthesis, as well as a large variety of organic molecules as the sole source of carbon and energy for growth. Light induces the enzymes, in this case an entire organelle, the chloroplast, that is required to use CO2 as the sole source of carbon and energy for growth. Ethanol, but not malate, inhibits the photoinduction of chloroplast enzymes and induces the synthesis of the glyoxylate cycle enzymes that comprise the unique metabolic pathway leading to two carbon, ethanol and acetate, assimilation...
2017: Advances in Experimental Medicine and Biology
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