Imperial College London


Faculty of MedicineDepartment of Infectious Disease

Research Associate



+44 (0)20 7594 3058alexander.webb1




Sir Alexander Fleming BuildingSouth Kensington Campus





During my Doctoral training at King's College London my research focused on the role of ATP-binding cassette (ABC) transporters in the physiology of Streptococcus mutans. This organism was originally isolated from carious lesions of the tooth. Using physiological and molecular studies I was able to: identify and characterise an ABC transporter (RnsBACD) involved in the uptake of ribonucleosides; identify and characterise an ABC transporter (MalXFGK) involved in the uptake of maltotriose and longer maltodextrins; further clarify the subtrates taken up by the previously characterised ABC transporter MsmEFGK; show that ABC-ATPases MalK and MsmK are interchangeable and can energise both the Msm and Mal transport systems; identify and characterise the principle phospoenolpyruvate-dependent phosphotransferase maltose system (MalT).

Previous postdoctoral projects include:

designing padlock probes (molecular inversion probes) for the identification of different Brucellae (in the group of Dr Sally J. Cutler).

identification and characterisation of two-enzymes system for glycolipid and polyglycerolphosphate lipoteichoic acid synthesis in the Gram-positive pathogen Listeria monocytogenes (in the group of Prof. Angelika Gründling).


Current research:

I am currenlty using synthetic biology to build affordable and molecular cell-based biosensors as generic platforms that can be applied to quickly and easily detect parasites via their protease signatures.

The parasitic infection Schistosomiasis affects over 200 million people worldwide, with estimates suggesting that a further 780 million people are at risk of infection. The causative agents are fluke worms of the Schistosoma genus, and infection only occurs when the cercarial larvae are able to penetrate the skin. To facilitate this, the cercariae secrete an elastase possessing defined substrate specificity. As a proof of concept, my project takes advantage of this property of the cercarial elastase, and has used it to design and create biosensors that are specific in targeting Schistosoma. The design of the biosensors is based on a two-pronged approach, 1) an accurate detection system which is targeted to the cercarial elastase, and 2) an easily measurable output. Using synthetic biology approaches we have engineered the biosensors to be “housed” in two bacterial chassis, Bacillus subtilis and Escherichia coli, and we have further designs that will enable for a cell-free based biosensor.



Kelwick RJR, Ricci L, Chee SM, et al., 2019, Cell-free prototyping strategies for enhancing the sustainable production of polyhydroxyalkanoates bioplastics, Synthetic Biology, Vol:3, ISSN:2397-7000

Webb AJ, Kelwick R, Freemont PS, 2017, Opportunities for applying whole-cell bioreporters towards parasite detection, Microbial Biotechnology, Vol:10, ISSN:1751-7915, Pages:244-249

Kelwick RJR, Webb AJ, MacDonald JT, et al., 2016, Development of a Bacillus subtilis cell-free transcription-translation system for prototyping regulatory elements, Metabolic Engineering, Vol:38, ISSN:1096-7184, Pages:370-381

Percy M, Karinou E, Webb A, et al., 2016, Identification of a lipoteichoic acid glycosyltransferase enzyme reveals that GW-domain containing proteins can be retained in the cell wall of Listeria monocytogenes in the absence of lipoteichoic acid or its modifications, Journal of Bacteriology, Vol:198, ISSN:1098-5530, Pages:2029-2042


Webb AJ, Allan F, Kelwick R, et al., 2018, Protease-based bioreporters for the detection of schistosome cercariae, American Society of Tropical Medicine and Hygiene (ASTMH) 67th Annual Meeting, New Orleans, Louisiana, USA

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