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James W. Coulton

Microbial Physiology/Genetics

Molecular biology of membrane proteins

Lyman Duff Medical Building
3775 University St., Room 403
Montreal, QC H3A 2B4
Tel: (514) 398-3929
Fax: (514) 398-7052
james [dot] coulton [at] mcgill [dot] ca (Email)

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Dr. Coulton is co-chair of CREATE-CDMC

Dr. Coulton is member of the Scientific Committee

Research Orientations

Public media and scientific literature repeatedly report the dramatic increase in resistance to currently available antibiotics by commonly encountered microbes. While there are multiple factors that contribute to the apparent ineffectiveness of antimicrobials, practitioners in hospitals are faced with significant problems in addressing bacterial infections. The scientific problem is that bacterial targets for anti-microbials are limited; new and effective targets need to be proposed. Members of the Coulton lab contribute basic science research; we address this urgent need for discovery of new targets. Because transport of essential nutrients across the cell envelope of Gram-negative bacteria including many serious human pathogens is poorly understood, our studies focus on these transport systems. Two membranes surround Gram-negative bacteria, making them inherently more resistant to antibiotics than Gram-positive bacteria. Our research in molecular microbiology and structural biology generates cutting edge science and suggests novel targets for antimicrobials. 

click on thumbnail image Coulton homepage figure

Scientific Background: Significance of Bacterial Iron Transport

To grow and divide, Gram-negative bacteria such as Escherichia coli must import nutrients from their surroundings. Their hallmark outer membrane provides protection from insults, but may also limit access of nutrients. Some compounds acquired by E. coli require a class of β barrel proteins that are termed receptors and in the Coulton lab, we study their properties. Transport of iron is particularly important: without sufficient iron supply, growth is limited. Outer membrane receptors show high affinity and specificity for Fe(III)-ligand complexes called siderophores (Mr ~ 750 Da) and they require energy derived from the proton motive force at the cytoplasmic membrane (CM). Energy delivery to OM receptors is mediated by transient interactions with TonB, a member of the integral CM complex, TonB-ExbB-ExbD. James Coulton is a charter member of the McGill Center for Structural Biology and principal scientist of the Montreal Integrated Genomics Group for Research on Infectious Pathogens, Canada Foundation for Innovation. Research funding support in the Coulton lab is from Canadian Institutes of Health Research (CIHR) and from Natural Sciences and Engineering Research Council (NSERC).

Membrane Proteomics: Canadian Research Network on Bacterial Pathogens of Swine

Canada's pork industry is annually valued at near $2.0 billion; 30% is in Québec. Pork production, the second most important agricultural activity in Québec, represents approximately 20% of agricultural revenue. Canadian losses attributed to related diseases reach $80 million per year. Growth retardation, deaths, medication and diagnostic laboratory fees account for these expenses. One of the most significant agents of infectious disease in the industry worldwide, the bacterial pathogen Actinobacillus pleuropneumoniae, causes porcine pleuropneumonia. Currently available vaccines have limited efficacy, little impact on morbidity, and major safety problems. Although whole-cell bacterins may reduce mortality after infection with the homologous serotype, they generally do not confer protection against challenge with heterologous (unrelated) serotypes. A safe, highly effective vaccine offering cross-protection against different serotypes is urgently needed. With pressure to reduce the use of antibiotics in feeds, vaccination against bacterial pathogens is the solution of choice. James Coulton is a charter member of the Canadian Research Network on Bacterial Pathogens of Swine: www.medvet.umontreal.ca/reseau/. The director of the Network, Mario Jacques, is collaborator on NSERC-funded projects (2005-2007) of the Coulton lab. Additional financial support is from Valorisation-Recherche Québec.

Selected Recent Publications

Plesa, M., Kim, J., Paquette, S.G., Gagnon, H., Ng-Thow-Hing, C., Gibbs, B.F., Hancock, M.A., Rosenblatt, D.S., and Coulton, J.W. (2010)  “Interaction between MMACHC and MMADHC, two human proteins participating in intracellular vitamin B12 metabolism.”  Molecular Genetics and Metabolism 102:139-148. 

James, K.J., Hancock, M.A., Gagnon, J.-N., and Coulton, J.W. (2009) “TonB interacts with BtuF, the Escherichia coli periplasmic binding protein for cyanocobalamin.” Biochemistry 48:9212-9220.

Gouré, J., Findlay, W.A., Deslandes, V., Bouevitch, A., Foote, S.J., MacInnes, J.I., Coulton, J.W., Nash, J.H., and Jacques, M. (2009) “Microarray-based comparative genomic profiling of reference strains and selected Canadian field isolates of Actinobacillus pleuropneumoniae”. BMC Genomics 10:88.

Chung, J.W., Jacques, M., and Coulton, J.W. (2008) “Outer membrane proteins and iron uptake of Actinobacillus pleuropneumoniae.” Pasteurellaceae, Biology, Genomics and Molecular Aspects, ed. P. Khunert and H. Christensen, pp. 144-175; Caister Academic Press, Norfolk, U.K.

James, K.J., Hancock, M.A., Moreau, V., Molina, F., and Coulton, J.W. (2008) "TonB induces conformational changes in surface-exposed loops of FhuA, outer membrane receptor of Escherichia coli." Protein Science 17:1679-1688.

Chung, J.W., Ng-Thow-Hing, C., Budman, L.I., Gibbs, B.F., Nash, J.H.E., Jacques, M., and Coulton, J.W. (2007) "Outer membrane proteome of Actinobacillus pleuropneumoniae: LC-MS/MS analyses validate in silico predictions." Proteomics 7:1854-1865.

Deslandes, V., Nash, J.H.E., Harel, J., Coulton, J.W., and Jacques, M. (2007) "Transcriptional profiling of Actinobacillus pleuropneumoniae under iron-restricted conditions." BMC Genomics 8:72 (20 pages).

Pawelek, P.D., Croteau, N., Ng-Thow-Hing, C., Khursigara, C.M., Moiseeva, N., Allaire, M., and Coulton, J.W. (2006) "Structure of TonB in complex with FhuA, E. coli outer membrane receptor." Science 312:1399-1402.

Carter, D.M., Miousse, I.R., Gagnon, J.-N., Martinez, É., Clements, A., Lee, J., Hancock, M.A., Gagnon, H., Pawelek, P.D., and Coulton, J.W. (2006) "Interactions between TonB from Escherichia coli and the periplasmic protein FhuD." Journal of Biological Chemistry 281:35413-35424.

Carter, D.M., Gagnon, J.-N., Damlaj, M., Mandava, S., Makowski, L., Rodi, D.J., Pawelek, P.D., and Coulton, J.W. (2006) "Phage display reveals multiple contact sites between FhuA, an outer membrane receptor of Escherichia coli, and TonB." Journal of Molecular Biology 357:236-251.

Lerner-Ellis, J.P., Tirone, J.C., Pawelek, P.D., Doré, C., Atkinson, J.L., Watkins, D., Morel, C.F., Fujiwara, T.M., Moras, E., Angela R. Hosack, A.R., Dunbar, G.V., Antonicka, H., Forgetta, V., Dobson, C.M., Leclerc, D., Gravel, R.A., Shoubridge, E.A., Coulton, J.W., Lepage, P., Rommens, J.M., Morgan, K., and Rosenblatt, D.S. (2006) "Identification of the gene responsible for methylmalonic aciduria and homocystinuria, cblC type." Nature Genetics 38:93-100.

Shakarji, L., Mikael, L.G., Srikumar, R., Kobisch, M., Coulton, J.W., and Jacques, M. (2006) "FhuA and HgbA, outer membrane proteins of Actinobacillus pleuropneumoniae: their role as virulence determinants." Canadian Journal of Microbiology 52:391-396.

Eisenhauer, H.A., Shames, S., Pawelek, P.D., and Coulton, J.W. (2005) "Siderophore transport through Escherichia coli outer membrane receptor FhuA with disulfide-tethered cork and barrel domains." Journal of Biological Chemistry 280:30574-30580.

Khursigara, C.M., De Crescenzo, G., Pawelek, P.D., and Coulton, J.W. (2005) "Deletion of the proline-rich region of TonB disrupts formation of a 2:1 complex with FhuA, an outer membrane receptor of Escherichia coli." Protein Science 14:1266-1273.

Khursigara, C.M., De Crescenzo, G., Pawelek, P.D., and Coulton, J.W. (2005) "Kinetic analyses reveal multiple steps in forming TonB-FhuA complexes from Escherichia coli." Biochemistry 44:3441-3453.

Khursigara, C.M., De Crescenzo, G., Pawelek, P.D., and Coulton, J.W. (2004) "Enhanced binding of TonB to a ligand-loaded outer membrane receptor; role of the oligomeric state of TonB in formation of a functional FhuA-TonB complex." Journal of Biological Chemistry 279:7405-7412.

Pawelek, P.D. and Coulton, J.W. (2004) "Hemoglobin-binding protein HgbA in the outer membrane of Actinobacillus pleuropneumoniae: homology modelling reveals regions of potential interactions with hemoglobin and heme." Journal of Molecular Graphics and Modelling 23:211-221.

Srikumar, R., Mikael, L.G., Pawelek, P.D., Khamessan, A., Gibbs, B.F., Jacques, M., and Coulton, J.W. (2004) "Molecular cloning of hemoglobin-binding protein HgbA in the outer membrane of Actinobacillus pleuropneumoniae." Microbiology 150:1723-1734.