Gordon J. King
University of Queensland
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Featured researches published by Gordon J. King.
Journal of Experimental Zoology | 1998
Gordon J. King; Roger S. Holmes
Human aldehyde dehydrogenase isozymes (ALDHs; EC 1.2.1.3) exhibit very high levels of activity in anterior eye tissues. Human corneal ALDH1 and ALDH3 isozymes are present as major soluble proteins (3% and 5%, respectively, of corneal soluble protein) and may play major roles in protecting the cornea against ultraviolet radiation (UVR)-induced tissue damage, as well as contributing directly to ultraviolet B (UV-B) photoreception. The human lens exhibits high levels of ALDH1 activity (1-2% of lens-soluble protein) and lower levels of ALDH3 activity. Kinetic analyses support a role for these enzymes in the metabolism of peroxidic aldehydes, which have been reported in ocular tissues.
Proceedings of the National Academy of Sciences of the United States of America | 2012
Michelle P. Christie; Andrew E. Whitten; Gordon J. King; Shu-Hong Hu; Russell Jarrott; Kai-En Chen; Anthony P. Duff; Philip Callow; Brett M. Collins; David E. James; Jennifer L. Martin
When nerve cells communicate, vesicles from one neuron fuse with the presynaptic membrane releasing chemicals that signal to the next. Similarly, when insulin binds its receptor on adipocytes or muscle, glucose transporter-4 vesicles fuse with the cell membrane, allowing glucose to be imported. These essential processes require the interaction of SNARE proteins on vesicle and cell membranes, as well as the enigmatic protein Munc18 that binds the SNARE protein Syntaxin. Here, we show that in solution the neuronal protein Syntaxin1a interacts with Munc18-1 whether or not the Syntaxin1a N-peptide is present. Conversely, the adipocyte protein Syntaxin4 does not bind its partner Munc18c unless the N-peptide is present. Solution-scattering data for the Munc18-1:Syntaxin1a complex in the absence of the N-peptide indicates that this complex adopts the inhibitory closed binding mode, exemplified by a crystal structure of the complex. However, when the N-peptide is present, the solution-scattering data indicate both Syntaxin1a and Syntaxin4 adopt extended conformations in complexes with their respective Munc18 partners. The low-resolution solution structure of the open Munc18:Syntaxin binding mode was modeled using data from cross-linking/mass spectrometry, small-angle X-ray scattering, and small-angle neutron scattering with contrast variation, indicating significant differences in Munc18:Syntaxin interactions compared with the closed binding mode. Overall, our results indicate that the neuronal Munc18-1:Syntaxin1a proteins can adopt two alternate and functionally distinct binding modes, closed and open, depending on the presence of the N-peptide, whereas Munc18c:Syntaxin4 adopts only the open binding mode.
Organic Letters | 2008
Priscila De Almeida Leone; Anthony Richard Carroll; Leanne Towerzey; Gordon J. King; Bernadette Marie McArdle; Gunther Kern; Stewart Fisher; John N. A. Hooper; Ronald J. Quinn
Bioassay-guided fractionation of the methanol extract of the Australian sponge Neopetrosia exigua led to the isolation of exiguaquinol (2), a new pentacyclic hydroquinone that inhibited Helicobacter pylori glutamate racemase (MurI) with an IC(50) of 4.4 microM. Its structure and relative configuration were assigned on the basis of spectroscopic data. Exiguaquinol (2), bearing a novel pentacyclic ring skeleton, is the first natural product to show inhibition of H. pylori MurI. Its protein-ligand modeling is also discussed.
Angewandte Chemie | 2014
Conan K. Wang; Gordon J. King; Susan E. Northfield; David J. Craik
Cyclic disulfide-rich peptides have exceptional stability and are promising frameworks for drug design. We were interested in obtaining X-ray structures of these peptides to assist in drug design applications, but disulfide-rich peptides can be notoriously difficult to crystallize. To overcome this limitation, we chemically synthesized the L- and D-forms of three prototypic cyclic disulfide-rich peptides: SFTI-1 (14-mer with one disulfide bond), cVc1.1 (22-mer with two disulfide bonds), and kB1 (29-mer with three disulfide bonds) for racemic crystallization studies. Facile crystal formation occurred from a racemic mixture of each peptide, giving structures solved at resolutions from 1.25 Å to 1.9 Å. Additionally, we obtained the quasi-racemic structures of two mutants of kB1, [G6A]kB1, and [V25A]kB1, which were solved at a resolution of 1.25 Å and 2.3 Å, respectively. The racemic crystallography approach appears to have broad utility in the structural biology of cyclic peptides.
Journal of Biological Chemistry | 2008
Nathan P. Cowieson; Gordon J. King; David Cookson; Ian R. Ross; Thomas Huber; David A. Hume; Bostjan Kobe; Jennifer L. Martin
Cortactin is a filamentous actin-binding protein that plays a pivotal role in translating environmental signals into coordinated rearrangement of the cytoskeleton. The dynamic reorganization of actin in the cytoskeleton drives processes including changes in cell morphology, cell migration, and phagocytosis. In general, structural proteins of the cytoskeleton bind in the N-terminal region of cortactin and regulatory proteins in the C-terminal region. Previous structural studies have reported an extended conformation for cortactin. It is therefore unclear how cortactin facilitates cross-talk between structural proteins and their regulators. In the study presented here, circular dichroism, chemical cross-linking, and small angle x-ray scattering are used to demonstrate that cortactin adopts a globular conformation, thereby bringing distant parts of the molecule into close proximity. In addition, the actin bundling activity of cortactin is characterized, showing that fully polymerized actin filaments are bundled into sheet-like structures. We present a low resolution structure that suggests how the various domains of cortactin interact to coordinate its array of binding partners at sites of actin branching.
Analytical Chemistry | 2008
Gordon J. King; Alun Jones; Bostjan Kobe; Thomas Huber; Dmitri Mouradov; David A. Hume; Ian L. Ross
Cross-linking can be used to identify spatial relationships between amino acids in proteins or protein complexes. A rapid and sensitive method for identifying the site of protein cross-linking using dithiobis(sulfosuccinimidyl propionate) (DTSSP) is presented and illustrated with experiments using murine cortactin, actin and acyl-CoA thioesterase. A characteristic 66 Da doublet, which arises from the asymmetric fragmentation of the disulfide of DTSSP-modified peptides, is observed in the mass spectra obtained under MALDI-TOF/TOF-MS conditions and allows rapid assignment of cross-links in modified proteins. This doublet is observed not only for linear cross-linked peptides but also in the mass spectra of cyclic cross-linked peptides when simultaneous fragmentation of the disulfide and the peptide backbone occurs. We suggest a likely mechanism for this fragmentation. We use guanidinylation of the cross-linked peptides with O-methyl isourea to extend the coverage of cross-linked peptides observed in this MALDI-MS technique. The methodology we report is robust and amenable to automation, and permits the analysis of native cystines along with those introduced by disulfide-containing cross-linkers.
Journal of Biological Chemistry | 2013
Norelle L. Daly; Louise Thorstholm; Kathryn P. Greenwood; Gordon J. King; Begoña Heras; Jennifer L. Martin; David J. Craik
Background: MCoTI-II is a potent serine protease inhibitor with a cyclic protein backbone. Results: Its three-dimensional structure and dynamics in complex with trypsin were determined using x-ray and NMR methods. Conclusion: The cyclic backbone of MCoTI-II participates in favorable interactions with trypsin. Significance: We demonstrate a new role for backbone cyclization in enhancing enzyme inhibitory activity. MCoTI-II is a head-to-tail cyclic peptide with potent trypsin inhibitory activity and, on the basis of its exceptional proteolytic stability, is a valuable template for the design of novel drug leads. Insights into inhibitor dynamics and interactions with biological targets are critical for drug design studies, particularly for protease targets. Here, we show that the cyclization and active site loops of MCoTI-II are flexible in solution, but when bound to trypsin, the active site loop converges to a single well defined conformation. This finding of reduced flexibility on binding is in contrast to a recent study on the homologous peptide MCoTI-I, which suggested that regions of the peptide are more flexible upon binding to trypsin. We provide a possible explanation for this discrepancy based on degradation of the complex over time. Our study also unexpectedly shows that the cyclization loop, not present in acyclic homologues, facilitates potent trypsin inhibitory activity by engaging in direct binding interactions with trypsin.
Inorganica Chimica Acta | 1997
Gordon J. King; Burt Zerner
Abstract We have prepared, for the first time, mixed-metal (Zn/Ni and Co/Ni) derivatives of the nickeloenzyme, urease. The mixed-metal derivatives, although possibly catalytically inert, provide a means for the further investigation of both the catalytic mechanism and coordination of the native nickel ions. A study of the specific activity of nickel-depleted urease indicates that the loss of one nickel ion is sufficient to render it inactive. Sulfite was found to play a key role in stabilising the urease-bound nickel. The visible spectrum of the pink Co/Ni urease is presented. Together, these results provide additional evidence for a difference in the ligation of the jack bean urease active-site nickel ions and comment on the possibility of a variety of ligation geometries. Examination of the sequences of the enzymes from Klebsiella aerogenes and the jack bean reveals that there is an exact match, residue for residue, between the critical ligating and active-site residues of the Klebsiella enzyme (α-chain residues: Asp 360, Cys 319, His 272, His 136, His 134 and carboxylated Lys 217) and those of the jack bean enzyme (Asp 633, Cys 592, His 545, His 519, His 409, His 407 and Lys 490), and this lends strong support to essentially identical mechanisms of action for the two enzymes.
Methods of Molecular Biology | 2008
Dmitri Mouradov; Gordon J. King; Ian R. Ross; Jade K. Forwood; David A. Hume; Andrea Sinz; Jennifer L. Martin; Bostjan Kobe; Thomas Huber
Cross-linking in combination with mass spectrometry can be used as a tool for structural modeling of protein complexes and multidomain proteins. Although cross-links represent only weak structural constraints, the combination of a limited set of experimental cross-links with molecular docking/modeling is often sufficient to determine the structure of a protein complex or multidomain protein at low resolution.
Journal of Biological Chemistry | 2013
Gordon J. King; Aurélie H. Chanson; Emily J. McCallum; Masaru Ohme-Takagi; Karl A. Byriel; Justine M. Hill; Jennifer L. Martin; Joshua S. Mylne
Background: VERNALIZATION1 (VRN1) binds DNA sequence nonspecifically in vitro, and its loss causes vernalization defects in plants. Results: Dominant suppression of VRN1 targets was lethal, and a triple mutant of the VRN1 B3 domain ablated DNA binding. Conclusion: The DNA-interacting surface of VRN1 B3 is defined. Significance: B3 domains are ubiquitous in plants, and learning how VRN1 B3 binds DNA is important for understanding B3-mediated processes. The B3 DNA-binding domain is a plant-specific domain found throughout the plant kingdom from the alga Chlamydomonas to grasses and flowering plants. Over 100 B3 domain-containing proteins are found in the model plant Arabidopsis thaliana, and one of these is critical for accelerating flowering in response to prolonged cold treatment, an epigenetic process called vernalization. Despite the specific phenotype of genetic vrn1 mutants, the VERNALIZATION1 (VRN1) protein localizes throughout the nucleus and shows sequence-nonspecific binding in vitro. In this work, we used a dominant repressor tag that overcomes genetic redundancy to show that VRN1 is involved in processes beyond vernalization that are essential for Arabidopsis development. To understand its sequence-nonspecific binding, we crystallized VRN1(208–341) and solved its crystal structure to 1.6 Å resolution using selenium/single-wavelength anomalous diffraction methods. The crystallized construct comprises the second VRN1 B3 domain and a preceding region conserved among VRN1 orthologs but absent in other B3 domains. We established the DNA-binding face using NMR and then mutated positively charged residues on this surface with a series of 16 Ala and Glu substitutions, ensuring that the protein fold was not disturbed using heteronuclear single quantum correlation NMR spectra. The triple mutant R249E/R289E/R296E was almost completely incapable of DNA binding in vitro. Thus, we have revealed that although VRN1 is sequence-nonspecific in DNA binding, it has a defined DNA-binding surface.