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Instruments / Technical Area	Publication Details	Published
	Structural characterization of a short-chain dehydrogenase/reductase from multi-drug resistant Acinetobacter baumannii Emily M. Cross , David Aragao , Kate M. Smith , Karli I. Shaw , Jeffrey D. Nanson , Shane R. Raidal , Jade K. Forwood Biochemical And Biophysical Research Communications DOI: 10.1016/j.bbrc.2019.08.056 Show Abstract ▼ Abstract: Acinetobacter baumannii (A. baumannii) is a clinically relevant, highly drug-resistant pathogen of global concern. An attractive approach to drug design is to specifically target the type II fatty acid synthesis (FASII) pathway which is critical in Gram negative bacteria and is significantly different to the type I fatty acid synthesis (FASI) pathway found in mammals. Enzymes involved in FASII include members of the short-chain dehydrogenase/reductase (SDR) superfamily. SDRs are capable of performing a diverse range of biochemical reactions against a broad spectrum of substrates whilst maintaining conserved structural features and sequence motifs. Here, we use X-ray crystallography to describe the structure of an SDR from the multi-drug resistant bacteria A. baumannii, previously annotated as a putative FASII FabG enzyme. The protein was recombinantly expressed, purified, and crystallized. The protein crystals diffracted to 2.0 Å and the structure revealed a FabG-like fold. Functional assays revealed, however, that the protein was not active against the FabG substrate, acetoacetyl-CoA. This study highlights that database annotations may show the necessary structural hallmarks of such proteins, however, they may not be able to cleave substrates that are typical of FabG enzymes. These results are important for the selection of target enzymes in future drug development.	Aug 2019
	MX2: a high-flux undulator microfocus beamline serving both the chemical and macromolecular crystallography communities at the Australian Synchrotron David Aragao , Jun Aishima , Hima Cherukuvada , Robert Clarken , Mark Clift , Nathan Philip Cowieson , Daniel Jesper Ericsson , Christine L. Gee , Sofia Macedo , Nathan Mudie , Santosh Panjikar , Jason Roy Price , Alan Riboldi-tunnicliffe , Robert Rostan , Rachel Williamson , Thomas Tudor Caradoc-davies Journal Of Synchrotron Radiation 25 DOI: 10.1107/S1600577518003120 Open Access Show Abstract ▼ Abstract: MX2 is an in-vacuum undulator-based crystallography beamline at the 3 GeV Australian Synchrotron. The beamline delivers hard X-rays in the energy range 4.8–21 keV to a focal spot of 22 × 12 µm FWHM (H × V). At 13 keV the flux at the sample is 3.4 × 1012 photons s−1. The beamline endstation allows robotic handling of cryogenic samples via an updated SSRL SAM robot. This beamline is ideal for weakly diffracting hard-to-crystallize proteins, virus particles, protein assemblies and nucleic acids as well as smaller molecules such as inorganic catalysts and organic drug molecules. The beamline is now mature and has enjoyed a full user program for the last nine years. This paper describes the beamline status, plans for its future and some recent scientific highlights	May 2018
	Structural insights into GDP-mediated regulation of a bacterial acyl-CoA thioesterase Yogesh B. Khandokar , Parul Srivastava , Nathan Cowieson , Subir Sarker , David Aragao , Shubagata Das , Kate M. Smith , Shane R. Raidal , Jade K. Forwood Journal Of Biological Chemistry DOI: 10.1074/jbc.M117.800227 Show Abstract ▼ Abstract: Thioesterases catalyze the cleavage of thioester bonds within many activated fatty acids and acyl-CoA substrates. They are expressed ubiquitously in both prokaryotes and eukaryotes and are subdivided into 25 thioesterase families according to their catalytic active site, protein oligomerization, and substrate specificity. While many of these enzyme families are well characterized in terms of function and substrate specificity, regulation across most thioesterase families is poorly understood. Here, we characterized a TE6 thioesterase from the bacterium Neisseria meningitidis. Structural analysis with X-ray crystallographic diffraction data to 2.0 Å revealed that each protein subunit harbors a hot dog fold and that the TE6 enzyme forms a hexamer with D3 symmetry. An assessment of thioesterase activity against a range of acyl-CoA substrates revealed greatest activity against acetyl-CoA, and structure-guided mutagenesis of putative active site residues identified Asn-24 and Asp-39 as being essential for activity. Our structural analysis revealed that six GDP nucleotides bound the enzyme in close proximity to an intersubunit disulfide bond interactions that covalently link thioesterase domains in a double hot dog dimer. Structure-guided mutagenesis of residues within the GDP-binding pocket identified Arg-93 as playing a key role in the nucleotide interaction and revealed that GDP is required for activity. All mutations were confirmed to be specific and not to have resulted from structural perturbations by X-ray crystallography. This is the first report of a bacterial GDP-regulated thioesterase and of covalent linkage of thioesterase domains through a disulfide bond, revealing structural similarities with ADP regulation in the human ACOT12 thioesterase.	Oct 2017
I24-Microfocus Macromolecular Crystallography	Ternary structure reveals mechanism of a membrane diacylglycerol kinase Dianfan Li , Phillip J. Stansfeld , Mark S. P. Sansom , Aaron Keogh , Lutz Vogeley , Nicole Howe , Joseph Lyons , David Aragao , Petra Fromme , Raimund Fromme , Shibom Basu , Ingo Grotjohann , Christopher Kupitz , Kimberley Rendek , Uwe Weierstall , Nadia A. Zatsepin , Vadim Cherezov , Wei Liu , Sateesh Bandaru , Niall J. English , Cornelius Gati , Anton Barty , Oleksandr Yefanov , Henry N. Chapman , Kay Diederichs , Marc Messerschmidt , Sébastien Boutet , Garth J. Williams , M. Marvin Seibert , Martin Caffrey Nature Communications 6 DOI: 10.1038/ncomms10140 Open Access Show Abstract ▼ Abstract: Diacylglycerol kinase catalyses the ATP-dependent conversion of diacylglycerol to phosphatidic acid in the plasma membrane of Escherichia coli. The small size of this integral membrane trimer, which has 121 residues per subunit, means that available protein must be used economically to craft three catalytic and substrate-binding sites centred about the membrane/cytosol interface. How nature has accomplished this extraordinary feat is revealed here in a crystal structure of the kinase captured as a ternary complex with bound lipid substrate and an ATP analogue. Residues, identified as essential for activity by mutagenesis, decorate the active site and are rationalized by the ternary structure. The γ-phosphate of the ATP analogue is positioned for direct transfer to the primary hydroxyl of the lipid whose acyl chain is in the membrane. A catalytic mechanism for this unique enzyme is proposed. The active site architecture shows clear evidence of having arisen by convergent evolution.	Dec 2015
I24-Microfocus Macromolecular Crystallography	Crystal structure of the integral membrane diacylglycerol kinase Dianfan Li , Joseph A. Lyons , Valerie Pye , Lutz Vogeley , David Aragao , Colin P. Kenyon , Syed T. A. Shah , Christine Doherty , Margaret Aherne , Martin Caffrey Nature 497 (7450), 521 - 524 DOI: 10.1038/nature12179 PMID: 23676677 Open Access Show Abstract ▼ Abstract: Diacylglycerol kinase catalyses the ATP-dependent phosphorylation of diacylglycerol to phosphatidic acid for use in shuttling water-soluble components to membrane-derived oligosaccharide and lipopolysaccharide in the cell envelope of Gram-negative bacteria1. For half a century, this 121-residue kinase has served as a model for investigating membrane protein enzymology1, 2, 3, 4, 5, 6, folding7, 8, assembly9, 10, 11, 12 and stability1, 13. Here we present crystal structures for three functional forms of this unique and paradigmatic kinase, one of which is wild type. These reveal a homo-trimeric enzyme with three transmembrane helices and an amino-terminal amphiphilic helix per monomer. Bound lipid substrate and docked ATP identify the putative active site that is of the composite, shared site type. The crystal structures rationalize extensive biochemical and biophysical data on the enzyme. They are, however, at variance with a published solution NMR model14 in that domain swapping, a key feature of the solution form, is not observed in the crystal structures.	May 2013
I24-Microfocus Macromolecular Crystallography	Structural insights into electron transfer in caa3-type cytochrome oxidase Joseph A. Lyons , David Aragao , Orla Slattery , Andrei V. Pisliakov , Tewfik Soulimane , Martin Caffrey Nature 487, 514 - 518 DOI: 10.1038/nature11182 PMID: 22763450 Open Access Show Abstract ▼ Abstract: Cytochrome c oxidase is a member of the haem copper oxidase superfamily (HCO)1. HCOs function as the terminal enzymes in the respiratory chain of mitochondria and aerobic prokaryotes, coupling molecular oxygen reduction to transmembrane proton pumping. Integral to the enzyme’s function is the transfer of electrons from cytochrome c to the oxidase via a transient association of the two proteins. Electron entry and exit are proposed to occur from the same site on cytochrome c2, 3, 4. Here we report the crystal structure of the caa3-type cytochrome oxidase from Thermus thermophilus, which has a covalently tethered cytochrome c domain. Crystals were grown in a bicontinuous mesophase using a synthetic short-chain monoacylglycerol as the hosting lipid. From the electron density map, at 2.36?Å resolution, a novel integral membrane subunit and a native glycoglycerophospholipid embedded in the complex were identified. Contrary to previous electron transfer mechanisms observed for soluble cytochrome c, the structure reveals the architecture of the electron transfer complex for the fused cupredoxin/cytochrome c domain, which implicates different sites on cytochrome c for electron entry and exit. Support for an alternative to the classical proton gate characteristic of this HCO class is presented.	Jul 2012

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