Browsing by Author "King, GF"

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    Source apportionment of ambient volatile organic compounds in major cities in Australia by positive matrix factorisation
    (Clean Air Society of Australia and New Zealand, 2008-05) Chan, AYC; Christensen, E; Golding, G; King, GF; Gore, W; Cohen, DD; Hawas, O; Stelcer, E; Simpson, R; Denison, L; Wong, N
    Source apportionment of the 6-daily, 24 h volatile organic compound (VOC) samples collected during 2003–2004 in Melbourne, Sydney and Brisbane was carried out using the Positive Matrix Factorisation software (PMF2). Fourteen C4-C10 VOCs were chosen for source apportionment. Biogenic emissions were not covered in this study because tracer VOCs such as isoprene were not measured. Five VOC source factors were identified, including the ‘evaporative / fuel distribution’ factor (contribute to 37% of the total mass of the 14 VOCs on average), the ‘vehicle exhaust / petrochemical industry’ factor (24%), the ‘biomass burning’ factor (13%), the ‘architectural surface coatings’ factor (5%) and the ‘other sources’ factor (14%). The relative contributions of the source factors to the ambient VOC concentration at the sampling sites were comparable to the relative emission loads of the local sources in Australian air emission inventories. The high contribution from evaporative emissions indicates that introduction of reduction measures for evaporative emissions could substantially reduce the VOC emissions in Australian cities. The total VOC mass and the contributions from vehicle related sources and biomass burning were higher in winter and autumn, while the contributions from surface coatings were higher in summer. © 2008, Clean Air Society of Australia and New Zealand
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    Structure of the KinA-Sda complex suggests an allosteric mechanism of histidine kinase inhibition
    (Elsevier, 2007-04-27) Whitten, AE; Jacques, DA; Hammouda, B; Hanley, TL; King, GF; Guss, JM; Trewhella, J; Langley, DB
    The Bacillus subtilis histidine kinase KinA controls activation of the transcription factor governing sporulation, SpoOA. The decision to sporulate involves KinA phosphorylating itself on a conserved histidine residue, after which the phosphate moiety is relayed via two other proteins to SpoOA. The DNA-damage checkpoint inhibitor Sda halts this pathway by binding KinA and blocking the autokinase reaction. We have performed small-angle X-ray scattering and neutron contrast variation studies on the complex formed by KinA and Sda. The data show that two Sda molecules bind to the base of the DHp dimerization domain of the KinA dimer. In this position Sda does riot appear to be able to sterically block the catalytic domain from accessing its target histidine, as previously proposed, but rather may effect an allosteric mode of inhibition involving transmission of the inhibitory signal via the four-helix bundle that forms the DHp domain. © 2007, Elsevier Ltd.
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    Structure of the sporulation histidine kinase inhibitor Sda from bacillus subtilis and insights into its solution state
    (International Union of Crystallography, 2009-06) Jacques, DA; Streamer, M; Rowland, SL; King, GF; Guss, JM; Trewhella, J; Langley, DB
    The crystal structure of the DNA-damage checkpoint inhibitor of sporulation, Sda, from Bacillus subtilis, has been solved by the MAD technique using selenomethionine-substituted protein. The structure closely resembles that previously solved by NMR, as well as the structure of a homologue from Geobacillus stearothermophilus solved in complex with the histidine kinase KinB. The structure contains three molecules in the asymmetric unit. The unusual trimeric arrangement, which lacks simple internal symmetry, appears to be preserved in solution based on an essentially ideal fit to previously acquired scattering data for Sda in solution. This interpretation contradicts previous findings that Sda was monomeric or dimeric in solution. This study demonstrates the difficulties that can be associated with the characterization of small proteins and the value of combining multiple biophysical techniques. It also emphasizes the importance of understanding the physical principles behind these techniques and therefore their limitations. © 2009, International Union of Crystallography