Heterologous production of cyclotide libraries in bacterial hosts for the discovery of novel antimicrobial agents

Lead Research Organisation: University of Warwick
Department Name: School of Life Sciences


Cyclotides are ribosomally synthesised peptides made of 28 to 47 amino acids. Those discovered thus far have been isolated from a variety of plant species including the Violaceae, Rubiaceae, Cucurbitaceae, Fabaceae, and Solanaceae families. Oldenlandia affinis (O. affinis) is one plant species that belongs to the Rubiaceae family and it is from this that the first cyclotide was discovered in the 1960s. Leaves of O. affinis were used by locals of the Congo to generate a tea that was then ingested. This was observed to aid in uterine contractions and consequently accelerate childbirth. The active ingredient in this concoction was discovered to be the cyclotide Kalata B1. In 1995 the structure of Kalata B1 was determined and since then 140 plus cyclotides have been uncovered with the entire family of cyclotides thought to contain more than 50,000 members. These vast array of cyclotides are now categorised into 3 main subtypes: the Mobius, bracelet and theorinine inhibitor families with kalata B1 belonging to the Mobius family. The Mobius and bracelet families are the most similar while trypsin inhibitors have the most difference in its sequence. Proteins are classed as cyclotides due to their containment of the cyclic cysteine knot (CCK) motif. They are head-to-tail cyclised and have 6 conserved cysteine residues forming 3 conserved disulphide bonds. This rigid structure give them their unique properties of being enzymatically, thermally and structurally stable for a peptide its size. Thus they have been shown to have anti-HIV, cytotoxic and antimicrobial activity all of which can be exploited and explored for biotechnological, pharmaceutical and industrial potential. This project focuses in particular on the antimicrobial activity, screening many to find potential candidates with potent bioactivity for exploration of its use as a potential alternative antibiotic.


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Studentship Projects

Project Reference Relationship Related To Start End Student Name
BB/M01116X/1 01/10/2015 30/09/2023
1897466 Studentship BB/M01116X/1 02/10/2017 30/09/2021 Rohini Ajaykumar
Description *Still ongoing work*

This work is on antibiotic resistance in bacteria important in the emergence of multi-drug resistance bacteria. Discovery is still ongoing but there have been new insights into the mechanism of the workings of the resistance of the antibiotic methylenomycin in Streptomyces bacteria. These results so far show that there is a blocking of the molecule that exports methylenomycin from the bacterial cell. The molecule that blocks this exporting mechanism is unblocked in the presence of methylenomycin. The specifics of this is being researched. This information would be valuable in manipulating this mechanism for biotechnological needs as to contribute vital knowledge into antibiotic resistance.
Exploitation Route The outcomes would provide valuable insights into the workings of antibiotic resistance. It could be used in biotechnology as an alternative mechanism to creating inducible expression of certain genes which at the moment, with the most popular method relies on expensive and hard to produce chemicals. Furthermore, this could be a starting point to finding new unknown mechanisms into resistance by bacteria of other antibiotics.
Sectors Healthcare,Pharmaceuticals and Medical Biotechnology

Description Soapbox Science Outreach 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach Regional
Primary Audience Public/other audiences
Results and Impact Event in which general public roughly 50 people coming and going, were engaged in science through a short talk and different activities, encouraging more into STEM.
Year(s) Of Engagement Activity 2019