Laura McCaughey is a Sir Henry Wellcome Postdoctoral Research Fellow working at the ithree institute (infection, immunology and innovation) at the University of Technology, Sydney (UTS) in collaboration with the University of Oxford.
Laura obtained an MSci in Forensic and Analytical Chemistry from the University of Strathclyde, Scotland, in 2010. During this degree Laura undertook a one-year placement at GlaxoSmithKline, Stevenage, UK, where she worked as an analytical chemist. She was then awarded a Wellcome trust PhD scholarship at the University of Glasgow. During her PhD Laura investigated the use of novel species-specific protein antibiotics, termed S-type pyocins, to kill the notoriously difficult-to-treat, and often multi-drug resistant, bacterium P. aeruginosa. Her research involved the discovery and mechanistic, structural and biophysical characterisation of known and novel pyocins and the in vivo testing of these antibiotics in a P. aeruginosa infection model.
Laura was awarded a four year Sir Henry Wellcome Postdoctoral Research Fellowship straight out of her PhD, which enabled her to establish international collaborations between UTS and the University of Oxford. Laura’s main research questions are ‘How do bacteria develop resistance to antibiotics and how can we identify novel approaches to antibiotic development to overcome this problem?’
Over the last four years Laura has been actively involved in highlighting the problem of antibiotic resistance, and the interventions necessary to prevent the problem escalating further, to the public.
Laura has disseminated results from her research at both national and international conferences including:
- 16th International Conference on Pseudomonas
- Lorne Protein Structure & Function
- Lorne Immunity and Infection
- ASM Sydney Micro
- New Horizons
- SGM spring conference
- Biochemical Society Bacteriocins focus meeting.
Laura is also a member of several organisations including:
- Australian Society for Biochemistry and Molecular Biology
- Franklin Women
- NSW EMCR Network
- Sydney Protein Group
- The American Society for Microbiology
- The Australian Society for Microbiology
The problem of antibiotic resistance, whereby bacteria become resistant to antibiotics used to kill them, has progressed to the stage where some bacteria are resistant to all available antibiotics. This means bacterial infections are causing longer illnesses and a greater risk of death. Therefore, new ways to kill bacteria are urgently required.
Bacteriocins are species-specific protein antibiotics used by bacteria for intraspecies competition that show huge potential for therapeutic development to treat drug-resistant bacteria. Lectin-like bacteriocins, including the P. aeruginosa-specific pyocin L1, are a class of structurally homologous, genus-specific bacteriocins for which the cytotoxic mechanism is unknown.
Laura's current research aims to identify the molecular target through which the lectin-like bacteriocins exert their cytotoxicity, and define its interaction with pyocin L1 and other homologous lectin-like bacteriocins.
Laura's fellowship is 100% research focused.
Agbowuro, AA, Hwang, J, Peel, E, Mazraani, R, Springwald, A, Marsh, JW, McCaughey, L, Gamble, AB, Huston, WM & Tyndall, JDA 2019, 'Structure-activity analysis of peptidic Chlamydia HtrA inhibitors.', Bioorganic & medicinal chemistry, vol. 27, no. 18, pp. 4185-4199.View/Download from: Publisher's site
Chlamydia trachomatis high temperature requirement A (CtHtrA) is a serine protease that performs proteolytic and chaperone functions in pathogenic Chlamydiae; and is seen as a prospective drug target. This study details the strategies employed in optimizing the irreversible CtHtrA inhibitor JO146 [Boc-Val-Pro-ValP(OPh)2] for potency and selectivity. A series of adaptations both at the warhead and specificity residues P1 and P3 yielded 23 analogues, which were tested in human neutrophil elastase (HNE) and CtHtrA enzyme assays as well as Chlamydia cell culture assays. Trypsin and chymotrypsin inhibition assays were also conducted to measure off-target selectivity. Replacing the phosphonate moiety with α-ketobenzothiazole produced a reversible analogue with considerable CtHtrA inhibition and cell culture activity. Tertiary leucine at P3 (8a) yielded approximately 33-fold increase in CtHtrA inhibitory activity, with an IC50 = 0.68 ± 0.02 µM against HNE, while valine at P1 retained the best anti-chlamydial activity. This study provides a pathway for obtaining clinically relevant inhibitors.
Agbowuro, AA, Mazraani, R, McCaughey, LC, Huston, WM, Gamble, AB & Tyndall, JDA 2018, 'Stereochemical basis for the anti-chlamydial activity of the phosphonate protease inhibitor JO146', Tetrahedron, vol. 74, no. 12, pp. 1184-1190.View/Download from: Publisher's site
© 2017 Elsevier Ltd JO146, a mixture of two diastereomers of a peptidic phosphonate inhibitor for Chlamydial HtrA (CtHtrA), has reported activity against Chlamydia species in both human and koala. In this study we isolated the individual diastereomers JO146-D1 and JO146-D2 (in ≥90% purity) and assessed their individual inhibitory activity against the serine protease human neutrophil elastase (HNE) which is structurally and functionally related to CtHtrA, as well as in Chlamydia trachomatis cell culture. JO146-D2 [S,S,R-Boc-Val-Pro-Val P (OPh) 2 ], the isomer with the physiologically relevant valine at P1, had an approximate 2.5 – fold increase in in vitro HNE inhibition potency over JO146-D1 [S,S,S-Boc-Val-Pro-Val P (OPh) 2 ] and greater than 100 – fold increase in cellular anti-chlamydial activity compared to JO146-D1 which possesses the unnatural valine at P1. JO146 and the individual diastereomers had excellent selectivity for the serine protease HNE over the potential off-target serine proteases trypsin and chymotrypsin. Docking studies supported the biological data with a geometrically unfavoured interaction observed between the P1 valine residue of JO146-D1 and the enzyme S1 sub-pocket.
White, P, Joshi, A, Rassam, P, Housden, NG, Kaminska, R, Goult, JD, Redfield, C, McCaughey, LC, Walker, D, Mohammed, S & Kleanthous, C 2017, 'Exploitation of an iron transporter for bacterial protein antibiotic import.', Proceedings of the National Academy of Sciences of the United States of America, vol. 114, no. 45, pp. 12051-12056.View/Download from: Publisher's site
Unlike their descendants, mitochondria and plastids, bacteria do not have dedicated protein import systems. However, paradoxically, import of protein bacteriocins, the mechanisms of which are poorly understood, underpins competition among pathogenic and commensal bacteria alike. Here, using X-ray crystallography, isothermal titration calorimetry, confocal fluorescence microscopy, and in vivo photoactivatable cross-linking of stalled translocation intermediates, we demonstrate how the iron transporter FpvAI in the opportunistic pathogen Pseudomonas aeruginosa is hijacked to translocate the bacteriocin pyocin S2 (pyoS2) across the outer membrane (OM). FpvAI is a TonB-dependent transporter (TBDT) that actively imports the small siderophore ferripyoverdine (Fe-Pvd) by coupling to the proton motive force (PMF) via the inner membrane (IM) protein TonB1. The crystal structure of the N-terminal domain of pyoS2 (pyoS2NTD) bound to FpvAI (Kd = 240 pM) reveals that the pyocin mimics Fe-Pvd, inducing the same conformational changes in the receptor. Mimicry leads to fluorescently labeled pyoS2NTD being imported into FpvAI-expressing P. aeruginosa cells by a process analogous to that used by bona fide TBDT ligands. PyoS2NTD induces unfolding by TonB1 of a force-labile portion of the plug domain that normally occludes the central channel of FpvAI. The pyocin is then dragged through this narrow channel following delivery of its own TonB1-binding epitope to the periplasm. Hence, energized nutrient transporters in bacteria also serve as rudimentary protein import systems, which, in the case of FpvAI, results in a protein antibiotic 60-fold bigger than the transporter's natural substrate being translocated across the OM.
Klein, A, Wojdyla, JA, Joshi, A, Josts, I, McCaughey, LC, Housden, NG, Kaminska, R, Byron, O, Walker, D & Kleanthous, C 2016, 'Structural and biophysical analysis of nuclease protein antibiotics', BIOCHEMICAL JOURNAL, vol. 473, pp. 2799-2812.View/Download from: Publisher's site
McCaughey, LC, Josts, I, Grinter, R, White, P, Byron, O, Tucker, NP, Matthews, JM, Kleanthous, C, Whitchurch, CB & Walker, D 2016, 'Discovery, characterization and in vivo activity of pyocin SD2, a protein antibiotic from Pseudomonas aeruginosa', BIOCHEMICAL JOURNAL, vol. 473, pp. 2345-2358.View/Download from: Publisher's site
McCaughey, LC, Ritchie, ND, Douce, GR, Evans, TJ & Walker, D 2016, 'Efficacy of species-specific protein antibiotics in a murine model of acute Pseudomonas aeruginosa lung infection', SCIENTIFIC REPORTS, vol. 6.View/Download from: Publisher's site
Joshi, A, Grinter, R, Josts, L, Chen, S, Wojdyla, JA, Lowe, ED, Kaminska, R, Sharp, C, McCaughey, L, Roszak, AW, Cogde, RJ, Byron, O, Walker, D & Kleanthous, C 2015, 'Structures of the Ultra-High-Affinity Protein-Protein Complexes of Pyocins S2 and AP41 and Their Cognate Immunity Proteins from Pseudomonas aeruginosa', JOURNAL OF MOLECULAR BIOLOGY, vol. 427, no. 17, pp. 2852-2866.View/Download from: Publisher's site
Grinter, R, Josts, I, Zeth, K, Roszak, AW, McCaughey, LC, Cogdell, RJ, Milner, JJ, Kelly, SM, Byron, O & Walker, D 2014, 'Structure of the atypical bacteriocin pectocin M2 implies a novel mechanism of protein uptake.', Molecular Microbiology, vol. 93, no. 2, pp. 234-246.View/Download from: Publisher's site
The colicin-like bacteriocins are potent protein antibiotics that have evolved to efficiently cross the outer membrane of Gram-negative bacteria by parasitizing nutrient uptake systems. We have structurally characterized the colicin M-like bacteriocin, pectocin M2, which is active against strains of Pectobacterium spp. This unusual bacteriocin lacks the intrinsically unstructured translocation domain that usually mediates translocation of these bacteriocins across the outer membrane, containing only a single globular ferredoxin domain connected to its cytotoxic domain by a flexible α-helix, which allows it to adopt two distinct conformations in solution. The ferredoxin domain of pectocin M2 is homologous to plant ferredoxins and allows pectocin M2 to parasitize a system utilized by Pectobacterium to obtain iron during infection of plants. Furthermore, we identify a novel ferredoxin-containing bacteriocin pectocin P, which possesses a cytotoxic domain homologous to lysozyme, illustrating that the ferredoxin domain acts as a generic delivery module for cytotoxic domains in Pectobacterium.
McCaughey, LC, Grinter, R, Josts, I, Roszak, AW, Waløen, KI, Cogdell, RJ, Milner, J, Evans, T, Kelly, S, Tucker, NP, Byron, O, Smith, B & Walker, D 2014, 'Lectin-like bacteriocins from Pseudomonas spp. utilise D-rhamnose containing lipopolysaccharide as a cellular receptor.', PLoS Pathogens, vol. 10, no. 2, pp. 1-15.View/Download from: Publisher's site
Lectin-like bacteriocins consist of tandem monocot mannose-binding domains and display a genus-specific killing activity. Here we show that pyocin L1, a novel member of this family from Pseudomonas aeruginosa, targets susceptible strains of this species through recognition of the common polysaccharide antigen (CPA) of P. aeruginosa lipopolysaccharide that is predominantly a homopolymer of D-rhamnose. Structural and biophysical analyses show that recognition of CPA occurs through the C-terminal carbohydrate-binding domain of pyocin L1 and that this interaction is a prerequisite for bactericidal activity. Further to this, we show that the previously described lectin-like bacteriocin putidacin L1 shows a similar carbohydrate-binding specificity, indicating that oligosaccharides containing D-rhamnose and not D-mannose, as was previously thought, are the physiologically relevant ligands for this group of bacteriocins. The widespread inclusion of d-rhamnose in the lipopolysaccharide of members of the genus Pseudomonas explains the unusual genus-specific activity of the lectin-like bacteriocins.
Brown, CL, Smith, K, McCaughey, L & Walker, D 2012, 'Colicin-like bacteriocins as novel therapeutic agents for the treatment of chronic biofilm-mediated infection', BIOCHEMICAL SOCIETY TRANSACTIONS, vol. 40, pp. 1549-1552.View/Download from: Publisher's site
Smith, K, Martin, L, Rinaldi, A, Rajendran, R, Ramage, G & Walker, D 2012, 'Activity of Pyocin S2 against Pseudomonas aeruginosa Biofilms', ANTIMICROBIAL AGENTS AND CHEMOTHERAPY, vol. 56, no. 3, pp. 1599-1601.View/Download from: Publisher's site
Martin, LC, Larmour, IA, Faulds, K & Graham, D 2010, 'Turning up the lights-fabrication of brighter SERRS nanotags', CHEMICAL COMMUNICATIONS, vol. 46, no. 29, pp. 5247-5249.View/Download from: Publisher's site
Nolan, LM, McCaughey, LC, Merjane, J, Turnbull, L & Whitchurch, CB, 'ChpC controls twitching motility-mediated expansion of Pseudomonas aeruginosa biofilms in response to serum albumin, mucin and oligopeptides'.View/Download from: Publisher's site
AbstractTwitching motility-mediated biofilm expansion occurs via coordinated, multi-cellular collective behaviour to allow bacteria to actively expand across surfaces. Type-IV pili (T4P) are cell-associated virulence factors which mediate this expansion via rounds of extension, surface attachment and retraction. The Chp chemosensory system is thought to respond to environmental signals to regulate the biogenesis, assembly and twitching motility function of T4P. In other well characterised chemosensory systems, methyl-accepting chemotaxis proteins (MCPs) feed environmental signals through a CheW adapter protein to the histidine kinase CheA to modulate motility. The Pseudomonas aeruginosa Chp system has two CheW adapter proteins, PilI and ChpC, and an MCP PilJ that likely interacts via PilI with the histidine kinase ChpA. It is thought that ChpC associates with other MCPs to feed environmental signals into the system, however no such signals have been identified. In the current study we show that ChpC is involved in the response to host-derived signals serum albumin, mucin and oligopeptides. We demonstrate that these signals stimulate an increase in twitching motility, as well as in levels of 3’-5’-cyclic adenosine monophosphate (cAMP) and surface-assembled T4P. Interestingly, our data shows that changes in cAMP and surface piliation levels are independent of ChpC but that the twitching motility response to these environmental signals requires ChpC. Based upon our data we propose a model whereby ChpC associates with an MCP other than PilJ to feed these environmental signals through the Chp system to control twitching motility. The MCP PilJ and the CheW adapter PilI then modulate T4P surface levels to allow the cell to continue to undergo twitching motility. Our study is the first to link environmental signals to the Chp chemosensory system and refines our understanding of how this system controls twitching...
Larmour, IA, Martin, LC, Faulds, K & Graham, D 2010, 'Silver nanoparticle dimers in solution, brighter nanotags and substrates for SMD', AIP Conference Proceedings, pp. 966-967.View/Download from: Publisher's site