Staff profile

Research Program

Trace nutrient metal ions (iron, manganese, zinc, copper) are essential for the function of nearly half of all proteins but they are toxic to cells if present in excess or if inserted into the wrong sites. The battle to control metal availability is now recognised as a key component of host-pathogen interactions in so-called “Nutritional Immunity” and there is growing interest in developing agents that manipulate nutrient metal level and location as new antimicrobial therapeutics.

Key questions that drive our research program are:

1. How does host-imposed, metal-linked nutritional immunity impact bacterial physiology?

2. How do bacteria adapt to the effects of nutritional immunity?

3. When/where in the host do bacterial pathogens encounter metal ions?

4. Can we learn from nature and manipulate metal levels and locations as new antibacterial approaches?

• Metals in microbiology
• Infectious diseases
• Microbial physiology
• Antimicrobial resistance
• Antimicrobial development

• Biomolecular Interactions

Chapter in book

• Turner, Andrew G., Ong, Cheryl-lynn Y., Walker, Mark J., Djoko, Karrera Y. & McEwan, Alastair G. (2017). Transition Metal Homeostasis in Streptococcus pyogenes and Streptococcus pneumoniae. In Microbiology of Metal Ions. 70: 123-191.
• Djoko, Karrera Y., Achard, Maud E.S. & McEwan, Alastair G. (2013). Copper in Immune Cells. In Encyclopedia of Inorganic and Bioinorganic Chemistry. 1-11.
• McEwan, Alastair G., Djoko, Karrera Y., Chen, Nathan H., Couñago, Rafael L.M., Kidd, Stephen P., Potter, Adam J. & Jennings, Michael P. (2011). Novel Bacterial MerR-Like Regulators: Their Role in the Response to Carbonyl and Nitrosative Stress. In Advances in Microbial Physiology. 58: 1-22.

Journal Article

• Stewart, Louisa J., Hong, YoungJin, Holmes, Isabel R., Firth, Samantha J., Ahmed, Yasmin, Quinn, Janet, Santos, Yazmin, Cobb, Steven L., Jakubovics, Nicholas S. & Djoko, Karrera Y. (2023). Salivary Antimicrobial Peptide Histatin-5 Does Not Display Zn(II)-Dependent or -Independent Activity against Streptococci. ACS Infectious Diseases 9(3): 631-642.
• Djoko, Karrera & Cavet, Jennifer (2022). Perspectives on Metals in Microbiology. Microbiology 168(7).
• O’Hern, Charlotte I. Z. & Djoko, Karrera Y. (2022). Copper Cytotoxicity: Cellular Casualties of Noncognate Coordination Chemistry. mBio 13(3): e00434-22.
• Brouwer, Stephan, Jespersen, Magnus G., Ong, Cheryl-lynn Y., De Oliveira, David M. P., Keller, Bernhard, Cork, Amanda J., Djoko, Karrera Y., Davies, Mark R. & Walker, Mark J. (2022). Streptococcus pyogenes Hijacks Host Glutathione for Growth and Innate Immune Evasion. mBio 13(3).
• Petit, Guillaume A., Hong, Yaoqin, Djoko, Karrera Y., Whitten, Andrew E., Furlong, Emily J., McCoy, Airlie J., Gulbis, Jacqueline M., Totsika, Makrina, Martin, Jennifer L. & Halili, Maria A. (2022). The suppressor of copper sensitivity protein C from Caulobacter crescentus is a trimeric disulfide isomerase that binds copper(I) with subpicomolar affinity. Acta Crystallographica Section D Structural Biology 78(3): 337.
• Stewart, Louisa J., Ong, Cheryl-lynn Y., Zhang, May M., Brouwer, Stephan, McIntyre, Liam, Davies, Mark R., Walker, Mark J., McEwan, Alastair G., Waldron, Kevin J. & Djoko, Karrera Y. (2020). Role of Glutathione in Buffering Excess Intracellular Copper in Streptococcus pyogenes. mBio 11(6): e02804-20.
• Stewart, Louisa J., Thaqi, Denis, Kobe, Bostjan, McEwan, Alastair G., Waldron, Kevin J. & Djoko, Karrera Y. (2019). Handling of nutrient copper in the bacterial envelope. Metallomics 11(1): 50-63.
• Djoko, Karrera Y., Achard, Maud E. S., Phan, Minh-Duy, Lo, Alvin W., Miraula, Manfredi, Prombhul, Sasiprapa, Hancock, Steven J., Peters, Kate M., Sidjabat, Hanna, Harris, Patrick N., Mitić, Nataša, Walsh, Timothy R., Anderson, Gregory J., Shafer, William M., Paterson, David L., Schenk, Gerhard, McEwan, Alastair G. & Schembri, Mark A. (2018). Copper ions and coordination complexes as novel carbapenem adjuvants. Antimicrobial Agents and Chemotherapy 62(2): e02280-17.
• Marsh, James W., Djoko, Karrera Y., McEwan, Alastair G. & Huston, Wilhelmina M. (2017). Copper(II)-bis(thiosemicarbazonato) complexes as anti-chlamydial agents. Pathogens and Disease 75(7): ftx084.
• Djoko, Karrera Y., Phan, Minh-Duy, Peters, Kate M., Walker, Mark J., Schembri, Mark A. & McEwan, Alastair G. (2017). Interplay between tolerance mechanisms to copper and acid stress in Escherichia coli. Proceedings of the National Academy of Sciences 114(26): 6818-6823.
• Turner, Andrew G., Ong, Cheryl-lynn Y., Djoko, Karrera Y., West, Nicholas P., Davies, Mark R., McEwan, Alastair G. & Walker, Mark J. (2017). The PerR-Regulated P1B-4-Type ATPase (PmtA) Acts as a Ferrous Iron Efflux Pump in Streptococcus pyogenes. Infection and Immunity 85(6): e00140-17.
• Couñago, Rafael M., Chen, Nathan H., Chang, Chiung-Wen, Djoko, Karrera Y., McEwan, Alastair G. & Kobe, Bostjan (2016). Structural basis of thiol-based regulation of formaldehyde detoxification in H. influenzae by a MerR regulator with no sensor region. Nucleic Acids Research 44(14): 6981-6993.
• Chen, Nathan H., Djoko, Karrera Y., Veyrier, Frédéric J. & McEwan, Alastair G. (2016). Formaldehyde Stress Responses in Bacterial Pathogens. Frontiers in Microbiology 7: 257.
• Djoko, Karrera Y., Goytia, Maira M., Donnelly, Paul S., Schembri, Mark A., Shafer, William M. & McEwan, Alastair G. (2015). Copper(II)-Bis(Thiosemicarbazonato) Complexes as Antibacterial Agents: Insights into Their Mode of Action and Potential as Therapeutics. Antimicrobial Agents and Chemotherapy 59(10): 6444-6453.
• Djoko, Karrera Y., Ong, Cheryl-lynn Y., Walker, Mark J. & McEwan, Alastair G. (2015). The Role of Copper and Zinc Toxicity in Innate Immune Defense against Bacterial Pathogens. Journal of Biological Chemistry 290(31): 18954-18961.
• Jen, F. E.- C., Djoko, K. Y., Bent, S. J., Day, C. J., McEwan, A. G. & Jennings, M. P. (2015). A genetic screen reveals a periplasmic copper chaperone required for nitrite reductase activity in pathogenic Neisseria. The FASEB Journal 29(9): 3828-3838.
• Djoko, Karrera Y., Donnelly, Paul S. & McEwan, Alastair G. (2014). Inhibition of respiratory Complex I by copper(ii)-bis(thiosemicarbazonato) complexes. Metallomics 6(12): 2250-2259.
• Atack, John M., Ibranovic, Ines, Ong, Cheryl-Lynn Y., Djoko, Karrera Y., Chen, Nathan H., vanden Hoven, Rachel, Jennings, Michael P., Edwards, Jennifer L. & McEwan, Alastair G. (2014). A Role for Lactate Dehydrogenases in the Survival of Neisseria gonorrhoeae in Human Polymorphonuclear Leukocytes and Cervical Epithelial Cells. The Journal of Infectious Diseases 210(8): 1311-1318.
• Djoko, Karrera Y., Paterson, Brett M., Donnelly, Paul S. & McEwan, Alastair G. (2014). Antimicrobial effects of copper(II) bis(thiosemicarbazonato) complexes provide new insight into their biochemical mode of action. Metallomics 6(4): 854-863.
• Djoko, Karrera Y. & McEwan, Alastair G. (2013). Antimicrobial Action of Copper Is Amplified via Inhibition of Heme Biosynthesis. ACS Chemical Biology 8(10): 2217-2223.
• Atack, J. M., Srikhanta, Y. N., K. Y., Welch, J. P., Hasri, N. H. M., Steichen, C. T., Vanden Hoven, R. N., Grimmond, S. M., Othman, D. S. M. P., Kappler, U., Apicella, M. A., Jennings, M. P., Edwards, J. L. & McEwan, A. G. (2013). Characterization of an ntrX Mutant of Neisseria gonorrhoeae Reveals a Response Regulator That Controls Expression of Respiratory Enzymes in Oxidase-Positive Proteobacteria. Journal of Bacteriology 195(11): 2632-2641.
• Chen, Nathan H., Couñago, Rafael M., Djoko, Karrera Y., Jennings, Michael P., Apicella, Michael A., Kobe, Bostjan & McEwan, Alastair G. (2013). A Glutathione-Dependent Detoxification System Is Required for Formaldehyde Resistance and Optimal Survival ofNeisseria meningitidisin Biofilms. Antioxidants & Redox Signaling 18(7): 743-755.
• Djoko, K. Y., Franiek, J. A., Edwards, J. L., Falsetta, M. L., Kidd, S. P., Potter, A. J., Chen, N. H., Apicella, M. A., Jennings, M. P. & McEwan, A. G. (2012). Phenotypic Characterization of a copA Mutant of Neisseria gonorrhoeae Identifies a Link between Copper and Nitrosative Stress. Infection and Immunity 80(3): 1065-1071.
• Kidd, Stephen P., Djoko, Karrera Y., Ng, JiaQi, Argente, M. Pilar, Jennings, Michael P. & McEwan, Alastair G. (2011). A novel nickel responsive MerR-like regulator, NimR, from Haemophilus influenzae. Metallomics 3(10): 1009-1018.
• Djoko, Karrera Y., Chong, Lee Xin, Wedd, Anthony G. & Xiao, Zhiguang (2010). Reaction Mechanisms of the Multicopper Oxidase CueO fromEscherichia coliSupport Its Functional Role as a Cuprous Oxidase. Journal of the American Chemical Society 132(6): 2005-2015.
• Drew, Simon C., Djoko, Karrera Y., Zhang, Lianyi, Koay, Melissa, Boas, John F., Pilbrow, John R., Xiao, Zhiguang, Barnham, Kevin J. & Wedd, Anthony G. (2008). Electron paramagnetic resonance characterization of the copper-resistance protein PcoC from Escherichia coli. JBIC Journal of Biological Inorganic Chemistry 13(6): 899-907.
• Djoko, Karrera Y., Xiao, Zhiguang & Wedd, Anthony G. (2008). Copper Resistance inE. coli: The Multicopper Oxidase PcoA Catalyzes Oxidation of Copper(I) in CuICuII‐PcoC. ChemBioChem 9(10): 1579-1582.
• Djoko, Karrera Y., Xiao, Zhiguang, Huffman, David L. & Wedd, Anthony G. (2007). Conserved Mechanism of Copper Binding and Transfer. A Comparison of the Copper-Resistance Proteins PcoC fromEscherichia coliand CopC fromPseudomonas syringae. Inorganic Chemistry 46(11): 4560-4568.
• Helfrich, Marcus R., Mangeney-Slavin, Lauren K., Long, M. Scott, Djoko, Karrera Y. & Keating, Christine D. (2002). Aqueous Phase Separation in Giant Vesicles. Journal of the American Chemical Society 124(45): 13374-13375.