Autotransporter proteins are the largest family of bacterial secreted proteins, and all of those characterized to date are virulence factors. One area we study is the characterization of the secretion pathway they use to exit the cell in the molecular detail. The second project focusses on LuxS which is the synthase of a bacterial cell-cell signalling molecule involved in population density related gene regulation. It also contributes to primary metabolism by catalysing one of the steps in the activated methyl cycle. We aim to decipher when each of these two functions becomes predominant in different bacteria including E. coli, Pseudomonas aeruginosa, Helicobacter pylori and Neisseria meningitidis. We have devised a novel high throughput method to quantify related metabolites and will use this to assess the impact of different quorum sensing pathways of bacterial metabolism and physiology. Other interests centre around a general curiosity to understand bacterial protein secretion including flagella assembly and the identification of novel antimicrobial targets. Bringing these together are two translational project, one to study single bacterial cells in real time during skin infections, and the other to design and build novel interactive devices to help children how to wash their hands, and thereby avoid spreading dangerous infectious agents.
I have extensive experience in molecular microbiology, including protein biochemistry and genetic engineering. I have also been involved in numerous studies of gene regulation and more recently am becoming familiar with analytical chemistry techniques aimed at ellucidating the metabolome of bacteria. Furthermore, I am expanding my knowledge of tissue engineering and vibrational spectroscopy alongside developing mechanisms to commercialise my research.
To convey knowledge about bacterial pathogenicity and to provide pastoral support and mentor students
Protein secretion enables the bacterium to place a battery of offence (toxins, proteasesetc) and defense (flagella, S-layers) systems beyond the boundaries of their outermembrane. The question `how do such large, sometimes folded structures exit the bacterial cell without causing cell leakage?' is fascinating, but little is known about the mechanics involved. I am interested in characterising these machineries in respect to autotransporter proteins, and determining their role in infection. Gene regulation (particularly that of virulence factors) plays a major role in cell survival and pathogenesis. In collaboration with Christoph Tang (Imperial College), Prof Paul Williams (Nottingham), Prof John Atherton (Nottingham), Prof Jerry Wells (Holland) and Klaus Winzer (Nottingham), I have been looking into the role of quorum sensing (cell-cell communication) in H. pylori, C. jejuni, P. aeruginosa, and N. meningitidis and linking this to pathogenicity. With the help of Dave Barrett (Nottingham) we are currently linking quorum sensing signal molecule production to its impact on cellular metabolism and the consequences this has to cell fitness and virulence (with Nigel Halliday, Cath Otori, Jean Dubern, Avika Ruparell). A major part of my research focuses on the mechanism of autotransporter protein secretion in E. coli (with Jeni Luckett [Nottingham], Rob Delahay [Nottingham], Ian Henderson [Birmingham] and Luis Angel Fernandez Herrero [Madrid]), Pseudomonas aeruginosa (with Miguel Camara [Nottingham], Stephan Heeb [Nottingham], Owen Darch [Nottingham] and Alain Filloux [Imperial College]), Bordetella pertussis (Francoise Jacob Dubuisson [Lille]) and H. pylori (Paul O'Toole, Ireland). Together we are dissecting the roles of potential accessory proteins in this process. Recently a new project has been initiated to study the secretion of botulinum toxin from Clostridia with Benjamin Blount, Soza Baban and Prof Nigel Minton (Nottingham). In addition, with Joel Segal (Engineering Nottingham), Jacqueline Randle (Nursing Nottingham), Brigitte Nerlich (Nottingham) and Caroline Windrum (Nottingham), interactive ways of improving the hand hygiene of children are being developed.
WAND, M.E., SOCKETT, R.E., EVANS, K.J., DOHERTY, N., SHARP, P.M., HARDIE, K.R. and WINZER, K., 2006. Helicobacter pylori FlhB function: the FlhB C-terminal homologue HP1575 acts as a "spare part" to permit flagellar export when the HP0770 FlhBCC domain is deleted Journal of Bacteriology. 188(21), 7531-7541 DOHERTY, N. C., SHEN, F., HALLIDAY, N. M., BARRETT, D. A., HARDIE, K. R., WINZER, K. and ATHERTON, J. C., 2010. Helicobacter pylori, LuxS is a key enzyme in cysteine provision through a reverse trassulfuration pathway Journal of Bacteriology. 192, 1184 - 1192 HEURLIER, K., VENDEVILLE, A., HALLIDAY, N., GREEN, A., WINZER, K., TANG, C.M. and HARDIE, K.R., 2009. Growth deficiencies of Neisseria meningitidis pfs and luxS mutants are not due to inactivation of quorum sensing Journal of Bacteriology. 191(4), 1293-1302
VENDEVILLE, A., WINZER, K., HEURLIER, K., TANG, C. M. and HARDIE, K. R., 2005. Making `sense' of metabolism: autoinducer-2, LuxS and pathogenic bacteria Nature Reviews: Microbiology. VOL 3(NUMB 5), 383-396
My Career has focused on the mechanism of bacterial protein secretion. In Cambridge I worked with Profs Colin Huges and Vassilis Koronakis on the type I dependent secretion of haemolysin (HlyA) from E. coli. Then, in Canada with Prof Tom Buckley on the type II dependent secretion of aerolysin by Aeromonas hydrophila. Moving to Institut Pasteur, Paris with Tony Pugsley, I switched to study the secretion apparatus, concentrating on the outer membrane component GspD and associated GspS. Subsequently I have studied AHL-dependent quorum sensing with Paul Williams (Nottingham) and the survival of H. pylori exposed to different stress conditions, particularly iron availability and oxidative stress, with the aim of discovering the function of the NapA protein (with Robert Logan and Peter Jenks). Moreover in collaboration with John Atherton I was involved in characterizing the link between the two major virulence factors of H. pylori (Vacuolating cytotoxin and Cag pathogenicity Island). Motility is an important virulence factor for H. pylori, and in collaboration with Dr Liz Sockett (Department of Genetics) and Klaus Winzer I studied the role of FlhB in flagella assembly and function. Helicobacter pylori pathogenesis, regulation of virulence factor production. These have been brought together in collaborations to look at the influence of LuxS upon motility in Helicobacter pylori, and the secretion of toxins via the flagella of Clostridia (with Profs John Atherton and Nigel Minton respectively).
I shall continue to study aspects of quorum sensing and bacterial protein secretion. In addition I am looking forward to a new project centred around determining simultaneous measurement of transcription, translation and metabolism during human skin infection. Finally I would be interested in further investigating bacterial membrane structure/integrity in particular in relation to organisms which are capable of shape changes such as Helicobacter pylori.