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Journal articleAyala R, Willhoft O, Aramayo R, et al., 2018,
Structure and regulation of the human INO80–nucleosome complex
, Nature, Vol: 556, Pages: 391-395, ISSN: 0028-0836Access to DNA within nucleosomes is required for a variety of processes in cells including transcription, replication and repair. Consequently, cells encode multiple systems that remodel nucleosomes. These complexes can be simple, involving one or a few protein subunits, or more complicated multi-subunit machines1. Biochemical studies2-4 have placed the motor domains of several remodellers on the superhelical location (SHL) 2 region of the nucleosome. Structural studies on Chd1 and Snf2 (RSC) in complex with nucleosomes5-7 have provided insights into the basic mechanism of nucleosome sliding by these complexes. However, how larger, multi-subunit remodelling complexes, such as INO80, interact with nucleosomes or how remodellers carry out functions such as nucleosome sliding8, histone exchange9, and nucleosome spacing10-12 remains poorly understood. Although some remodellers work as monomers13, others work as highly cooperative dimers11,14,15. Here we present the structure of the INO80 chromatin remodeller with a bound nucleosome revealing that INO80 interacts with nucleosomes in a unique manner with the motor domains located at the entry point to the wrap around the histone core rather than at SHL2. The Arp5-Ies6 module of INO80 makes additional contacts on the opposite side of the nucleosome. This unique arrangement allows the H3 tails of the nucleosome to play a role in regulation, differing from other characterised remodellers.
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Journal articleImseng S, Aylett CHS, Maier T, 2018,
Architecture and activation of phosphatidylinositol 3-kinase related kinases
, Current Opinion in Structural Biology, Vol: 49, Pages: 177-189, ISSN: 0959-440XThe phosphatidylinositol 3-kinase related protein kinases (PIKKs) are key to the regulation of a variety of eukaryotic cellular processes including DNA repair and growth regulation. While these massive proteins had long resisted structural analysis, recent advances in electron cryo-microscopy have now facilitated structural analysis of the major examples of PIKKs, including mTOR, DNA-PK, ATM, ATR and TRAPP/Tra1. In these PIKKs, the carboxy-terminal kinase domains and their proximal regions are structurally conserved. The structural organization of their extensive amino-terminal repeat regions, however, as well as their oligomeric organization and their interactions with accessory proteins, differ markedly amongst PIKKs. This architectural divergence provides the structural basis for the complex regulatory roles and functional diversity of PIKKs.
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Journal articleRiglar DT, Silver PA, 2018,
Engineering bacteria for diagnostic and therapeutic applications
, Nature Reviews Microbiology, Vol: 16, Pages: 214-225, ISSN: 1740-1526Our ability to generate bacterial strains with unique and increasingly complex functions has rapidly expanded in recent times. The capacity for DNA synthesis is increasing and costing less; new tools are being developed for fast, large-scale genetic manipulation; and more tested genetic parts are available for use, as is the knowledge of how to use them effectively. These advances promise to unlock an exciting array of 'smart' bacteria for clinical use but will also challenge scientists to better optimize preclinical testing regimes for early identification and validation of promising strains and strategies. Here, we review recent advances in the development and testing of engineered bacterial diagnostics and therapeutics. We highlight new technologies that will assist the development of more complex, robust and reliable engineered bacteria for future clinical applications, and we discuss approaches to more efficiently evaluate engineered strains throughout their preclinical development.
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Journal articleStuttfeld E, Aylett CH, Imseng S, et al., 2018,
Architecture of the human mTORC2 core complex
, eLife, Vol: 7, ISSN: 2050-084XThe mammalian target of rapamycin (mTOR) is a key protein kinase controlling cellular metabolism and growth. It is part of the two structurally and functionally distinct multiprotein complexes mTORC1 and mTORC2. Dysregulation of mTOR occurs in diabetes, cancer and neurological disease. We report the architecture of human mTORC2 at intermediate resolution, revealing a conserved binding site for accessory proteins on mTOR and explaining the structural basis for the rapamycin insensitivity of the complex.
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Journal articleHazel P, Kroll SHB, Bondke A, et al., 2018,
Corrigendum: Inhibitor selectivity for cyclin-dependent kinase 7: a structural, thermodynamic, and modelling study
, ChemMedChem, Vol: 13, Pages: 207-207, ISSN: 1860-7187 -
Journal articleFreemont PS, Salih O, He S, et al., 2018,
Atomic Structure of Type VI Contractile Sheath from Pseudomonas aeruginosa
, Structure, Vol: 26, Pages: 329-336.e3, ISSN: 0969-2126Pseudomonas aeruginosa has three type VI secretion systems (T6SSs), H1-, H2-, and H3-T6SS, each belonging to a distinct group. The two T6SS components, TssB/VipA and TssC/VipB, assemble to form tubules that conserve structural/functional homology with tail sheaths of contractile bacteriophages and pyocins. Here, we used cryoelectron microscopy to solve the structure of the H1-T6SS P. aeruginosa TssB1C1 sheath at 3.3 Å resolution. Our structure allowed us to resolve some features of the T6SS sheath that were not resolved in the Vibrio cholerae VipAB and Francisella tularensis IglAB structures. Comparison with sheath structures from other contractile machines, including T4 phage and R-type pyocins, provides a better understanding of how these systems have conserved similar functions/mechanisms despite evolution. We used the P. aeruginosa R2 pyocin as a structural template to build an atomic model of the TssB1C1 sheath in its extended conformation, allowing us to propose a coiled-spring-like mechanism for T6SS sheath contraction.
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Book chapterLai H-E, Moore S, Polizzi K, et al., 2018,
EcoFlex: A Multifunctional MoClo Kit for E. coli Synthetic Biology.
, Pages: 429-444Development of advanced synthetic biology tools is always in demand since they act as a platform technology to enable rapid prototyping of biological constructs in a high-throughput manner. EcoFlex is a modular cloning (MoClo) kit for Escherichia coli and is based on the Golden Gate principles, whereby Type IIS restriction enzymes (BsaI, BsmBI, BpiI) are used to construct modular genetic elements (biological parts) in a bottom-up approach. Here, we describe a collection of plasmids that stores various biological parts including promoters, RBSs, terminators, ORFs, and destination vectors, each encoding compatible overhangs allowing hierarchical assembly into single transcription units or a full-length polycistronic operon or biosynthetic pathway. A secondary module cloning site is also available for pathway optimization, in order to limit library size if necessary. Here, we show the utility of EcoFlex using the violacein biosynthesis pathway as an example.
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Journal articleZhang X, Aramayo RJ, Willhoft O, et al., 2017,
CryoEM structures of the human INO80 chromatin remodelling complex
, Nature Structural and Molecular Biology, Vol: 25, Pages: 37-44, ISSN: 1545-9985Access to chromatin for processes such as DNA repair and transcription requires the sliding of nucleosomes along DNA. The multi-subunit INO80 chromatin remodelling complex has a particular role in DNA repair. Here we present the cryo electron microscopy structures of the active core complex of human INO80 at 9.6 Å with portions at 4.1 Å resolution along with reconstructions of combinations of subunits. Together these structures reveal the architecture of the INO80 complex, including Ino80 and actin-related proteins, which is assembled around a single Tip49a (RUVBL1) and Tip49b (RUVBL2) AAA+ heterohexamer. An unusual spoked-wheel structural domain of the Ino80 subunit is engulfed by this heterohexamer and the intimate association of this Ino80 domain with the heterohexamer is at the core of the complex. We also identify a cleft in RUVBL1 and RUVBL2, which forms a major interaction site for partner proteins and likely communicates partner-interactions with its nucleotide binding sites.
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Journal articleKopniczky M, freemont P, Moore S,
Multilevel regulation and translational switches in synthetic biology
, IEEE Transactions on Biomedical Circuits and Systems, ISSN: 1940-9990In contrast to the versatility of regulatory mechanisms in natural systems, synthetic genetic circuits have been so far predominantly composed of transcriptionally regulated modules. This is about to change as the repertoire of foundational tools for post-transcriptional regulation is quickly expanding. We provide an overview of the different types of translational regulators: protein, small molecule and RNA responsive and we describe the new emerging circuit designs utilizing these tools. There are several advantages of achieving multilevel regulation via translational switches and it is likely that such designs will have the greatest and earliest impact in mammalian synthetic biology for regenerative medicine and gene therapy applications.
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