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Despite decades of study, the mechanisms that HIV employs at certain steps of its replication cycle remain relatively nebulous. One such step involves the viral regulatory protein, Rev, whose principal function is to affect the nuclear export of a majority of the viral mRNA transcripts that are produced during infection. Rev achieves the specific transport of the viral RNAs by oligomerizing onto the Rev response element, a highly-structured RNA motif within an env intron. Without such RNA ...
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The proton dependent oligopeptide transporters (POTs) are a large family of integral membrane proteins that use the inwardly directed proton electrochemical gradient to transport small peptides, amino acids and nitrate across cellular membranes in both pro- and eukaryotic cells. Evolutionarily the POT family sits within the much larger Major Facilitator Superfamily (MFS), members of which contain a common structural motif of 12 transmembrane-spanning alpha-helical segments. The human genome ...
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Rhomboids belong to the family of intramembrane proteases that use a catalytic dyad of serine and histidine for proteolysis of substrate transmembrane proteins. Conserved in both prokaryotes and eukaryotes, they regulate diverse cellular processes such as intercellular signalling, parasitic invasion of host cells, and mitochondrial morphology. Their importance in biology provides a strong incentive to understand the mechanism of these unusual enzymes for identification of specific ...
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Diamond is one of the most interesting materials for many applications in engineering, electronics, jewellery, and synchrotron radiation instrumentation. Chemical vapour deposition techniques allow diamond growth on a range of substrates, and in a range of crystalline quality. Nano-crystalline diamond has been proposed for use in biosensors and nanolithography as it can be deposited with sub-µm resolution. X-ray optics made of diamond are almost transparent, very strong, and are subject to ...
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The relentless drive for greater information storage capacity in physically smaller devices has pushed the size of components to scales where quantum mechanical effects become important. To aid such an increase in information density, both the electron spin and charge are exploited in the field of spin transport electronics; hence the portmanteau spintronics. The idea is to combine the characteristics of existing magnetic devices with semiconductor devices in order to realise a new ...
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Spintronic devices make use of the electron spin to store, recall and process data. Examples include the spin-valve read head, which has produced orders-of-magnitude improvements in magnetic data storage densities, and cutting-edge nonvolatile magnetic random access memory. Over the past decade, ferromagnetic (FM) semiconductors have emerged as new candidates for spintronic applications, offering the prospect of combining high density storage and gate-controlled logic in a single material.1 ...
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2011 is the International Year of Chemistry and also sees the launch of Sustainability as a University-wide societal engagement theme at Newcastle, so it is appropriate for significant progress to be made in structural characterisation at Diamond Light Source as part of a Newcastle School of Chemistry project developing carbon capture technology and its application in making ‘green’ solvents that, in turn, can be used for environmentally friendly processes to synthesise useful chemicals. ...
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Thin films comprising ordered stacks of purple membrane (PM) sheets containing the light-driven proton pump bacteriorhodopsin, were infiltrated with methacrylic acid monomers to produce intercalated lamellar bionanocomposites with expanded interlayer spacing. Subsequent in situ polymerization and crosslinking of the guest methacrylic acid molecules resulted in intercalated poly(acrylate)/PM free-standing films, which showed increased stability in water, structural integrity and enhanced ...
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To establish successful infection, a retrovirus must insert a DNA replica of its genome into host cell chromosomal DNA. This process is orchestrated by integrase, a viral enzyme that belongs to the DDE(D) nucleotidyltransferase/transposase superfamily. A tetramer of integrase assembles on viral DNA ends forming a highly stable nucleoprotein complex termed intasome 1,2. The intasome engages chromosomal DNA within a target capture complex to carry out strand transfer, irreversibly joining the ...
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Lassa fever virus kills more than five thousand people in West Africa every year, with many survivors having hearing and neurological problems.1 As no vaccine or effective drugs are available, and the infection can transmit from person to person, the Lassa fever virus is classed as a hazard group four virus and is regarded as a potential biological weapon. The nucleoprotein of Lassa fever is the most abundant protein in the virus and plays essential roles in virus translation, transcription, ...
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The serpins are a family of proteins of special interest to structural biologists because of their ability to spontaneously undergo a profound change in conformation.1 This conformational transition reflects the prime role of the serpins as protease inhibitors but it has also been adapted in individual serpins to allow the modulation of their function.2 A series of structures over the last 20 years has shown how this flexibility enables the serpins to act as controlling factors in key ...
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In metallo-supramolecular chemistry small molecules are organised into larger, more complex assemblies through the use of reversible metal-ligand coordination interactions. These assemblies are highly complicated and are often polyhedral or prismatic in shape and of nanometre scale. Given the right conditions they effectively make themselves in a process called self-assembly. They may have significant internal space where other molecules can be trapped or even react, acting like nano-sized ...
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Anions are of central importance in natural, medical, and industrial systems: mis-regulation of chloride channels is known to be a cause of cystic fibrosis; use of nitrates and phosphates in fertilisers has caused enormous environmental damage through eutrophication; and pertechnetate is a radioactive bi-product of the nuclear industry. Stimulated by the fundamental roles negatively charged species play in these areas, there has been enormous interest in the field of supramolecular anion ...
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Piezoelectric materials are mainstream components for both consumer and industrial applications in a market worth an estimated $10.7 billion annually. The vast majority of this realm is served by the ceramic lead zirconate titanate (PZT), which contains up to 60% by weight of lead; there is considerable international effort at present to find viable lead free alternatives to PZT. High-energy synchrotron radiation available on the Extreme Conditions Beamline, I15 at Diamond Light Source has ...
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We have made use of the I15 beamline at Diamond Light Source to investigate the high pressure behaviour of Ti2.85O4N, a novel oxynitride synthesized by the unusual route of atmospheric pressure chemical vapour deposition, at pressures up to 68 GPa. At ambient pressure this phase adopts the pseudo-brookite Cmcm structure, and anisotropic compression was observed up 18 GPa, at which pressure a first order phase transition was observed to new orthorhombic (Pmc21) structure. Further compression ...
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Tungstates of 3d-transition metals form an important family of inorganic materials with applications in various fields. CuWO4 is one of them, being well known as a semiconductor with technological applications in scintillator detectors, laser hosts, photoanodes, optical fibers, etc. In the last few years it has also attracted attention as a multiferroic material with an intriguing magnetic phase diagram. CuWO4 has been studied at ambient pressure to characterize its optical, magnetic, and ...
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Iron is necessary for many cellular reactions and is therefore an essential nutrient for all living organisms. However, insolubility and toxicity of iron make its acquisition and processing a great challenge for living organisms. Thus to overcome such difficulties, bacteria have developed iron homeostasis mechanisms that involve control of three key processes: iron uptake, iron utilisation and storage of excess iron. Among these processes, uptake of iron plays a particularly crucial role for ...
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Growing concerns about fuel security and global warming have made the development and use of sustainable (low carbon) sources of energy an increasingly attractive proposition. Harvesting energy from sunlight at low-cost using photovoltaic devices is a rapidly growing research area, with organic based photovoltaics (OPVs) attracting particular interest as they have the potential advantages of low manufacturing-cost (as they are fabricated using solution based techniques) and ...
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Spherulites are roughly spherical structures, and their name derives from the Greek for ‘ball’ and ‘stone’. Spherulites occur in various forms in nature. Those that form from polymers self-assemble into arrays of fibres that radiate out from the centre of the structure, and they are typically observed with diameters on the micrometre-scale. The arrangement of the fibres in the spherulite gives rise to birefringence, which may be observed when the spherulite is placed between crossed ...
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Templates are widely used to arrange molecular components so that they can be covalently linked to generate complex molecules that are not readily accessible by classical synthetic methods. Nature uses sophisticated templates such as the ribosome, whereas chemists use simple ions or small molecules. But as we tackle the synthesis of larger targets, we require larger templates — which themselves become synthetically challenging. Recently, we have shown that Vernier complexes can solve this ...
