36 research outputs found

    The Earliest Europeans

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    The Earliest Europeans explores the early origins of man in Europe through the perspective of ‘a year in the life’: how hominins in the Lower Palaeolithic coped with the year-round practical challenges of mid-latitude Europe with its distinctive temperatures, seasonality patterns, and available resources. Current research has provided increasingly robust archaeological and Quaternary Science records, but there are ongoing uncertainties as to both the earliest Europeans’ specific survival strategies and behaviours, and the character of their dispersals into Europe. In short, how sustained and ‘successful’ were the individual phases of European occupation by Lower Palaeolithic hominins and what sorts of ‘human’ where they

    Dna2 is a structure-specific nuclease, with affinity for 5'-flap intermediates

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    Dna2 is a nuclease/helicase with proposed roles in DNA replication, double-strand break repair and telomere maintenance. For each role Dna2 is proposed to process DNA substrates with a 5'-flap. To date, however, Dna2 has not revealed a preference for binding or cleavage of flaps over single-stranded DNA. Using DNA binding competition assays we found that Dna2 has substrate structure specificity. The nuclease displayed a strong preference for binding substrates with a 5'-flap or some variations of flap structure. Further analysis revealed that Dna2 recognized and bound both the single-stranded flap and portions of the duplex region immediately downstream of the flap. A model is proposed in which Dna2 first binds to a flap base, and then the flap threads through the protein with periodic cleavage, to a terminal flap length of ~5 nt. This resembles the mechanism of flap endonuclease 1, consistent with cooperation of these two proteins in flap processing

    Dimerisation induced formation of the active site and the identification of three metal sites in EAL-phosphodiesterases

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    The bacterial second messenger cyclic di-3′,5′-guanosine monophosphate (c-di-GMP) is a key regulator of bacterial motility and virulence. As high levels of c-di-GMP are associated with the biofilm lifestyle, c-di-GMP hydrolysing phosphodiesterases (PDEs) have been identified as key targets to aid development of novel strategies to treat chronic infection by exploiting biofilm dispersal. We have studied the EAL signature motif-containing phosphodiesterase domains from the Pseudomonas aeruginosa proteins PA3825 (PA3825EAL) and PA1727 (MucREAL). Different dimerisation interfaces allow us to identify interface independent principles of enzyme regulation. Unlike previously characterised two-metal binding EAL-phosphodiesterases, PA3825EAL in complex with pGpG provides a model for a third metal site. The third metal is positioned to stabilise the negative charge of the 5′-phosphate, and thus three metals could be required for catalysis in analogy to other nucleases. This newly uncovered variation in metal coordination may provide a further level of bacterial PDE regulation

    Use of green fluorescent protein for the analysis of protein-protein and protein-DNA interactions

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    Restriction modification (RM) systems play a crucial role in preventing the entry of foreign DNA into the bacterial cell. The best studied Type I RM system is EcoKI from Escherichia coli K12. Both bacteriophage and conjugative plasmids have developed a variety of strategies to circumvent the host RM system. One such strategy involves the production of antirestriction proteins that mimic a short segment of DNA and efficiently inhibit the RM system. The main aim of this project was to analyse the interaction of EcoKI and its cognate methylase (MTase) with the T7 antirestriction protein, known as overcome classical restriction (Ocr), and various ArdA antirestriction proteins. Currently, there is a paucity of structural data on the complex formed between the Type I system and the antirestriction proteins. The aim of this work was twofold; (i) compare the interaction of MTase with DNA and Ocr and (ii) quantify the strength of interaction between MTase and various ArdA proteins. The MTase was fused to the Green Fluorescent Protein (GFP) to facilitate determination of the orientation of interaction with DNA and Ocr. Time resolved fluorescence measurements were carried out using the GFP-MTase fusion to determine the fluorescence lifetime and anisotropy decay. These experiments were conducted using a time resolved fluorescence instrument fabricated in-house. The values determined in these experiments were then used to perform fluorescence resonance energy transfer (FRET) measurements with fluorescently labelled DNA or Ocr. These measurements gave information concerning the relative orientation of the MTase with either DNA or Ocr. The GFP-MTase fusion was also used to quantify the strength of interaction with various ArdA proteins. Previous attempts to determine the strength of interaction between MTase and ArdA proteins by employing conventional techniques have been unsuccessful. Therefore, a novel method was developed that exploits the interaction of MTase with a cation exchange medium, which can subsequently be displaced upon binding to ArdA. This method facilitated the determination, for the first time, of a set of binding affinities for the MTase and ArdA interaction

    AI is a viable alternative to high throughput screening: a 318-target study

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    : High throughput screening (HTS) is routinely used to identify bioactive small molecules. This requires physical compounds, which limits coverage of accessible chemical space. Computational approaches combined with vast on-demand chemical libraries can access far greater chemical space, provided that the predictive accuracy is sufficient to identify useful molecules. Through the largest and most diverse virtual HTS campaign reported to date, comprising 318 individual projects, we demonstrate that our AtomNet® convolutional neural network successfully finds novel hits across every major therapeutic area and protein class. We address historical limitations of computational screening by demonstrating success for target proteins without known binders, high-quality X-ray crystal structures, or manual cherry-picking of compounds. We show that the molecules selected by the AtomNet® model are novel drug-like scaffolds rather than minor modifications to known bioactive compounds. Our empirical results suggest that computational methods can substantially replace HTS as the first step of small-molecule drug discovery
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