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Erasing the superintegron to understand the role of chromosomal integrons in bacterial evolution

Project description

Insight into mobile genetic elements in bacteria: lessons from cholera

Bacterial genetic elements such as integrons are responsible for bacterial evolution through the transfer of genes. Mobile integrons are implicated in the emergence of antibiotic resistance that has become a major health challenge. Scientists of the EU-funded KryptonInt project are investigating the superintegron (SI), a sedentary chromosomal integron (SCI) located in the chromosome of Vibrio cholerae, the causative agent of Cholera disease. By deleting the SI, researchers will study the role and adaptive value of integrons in nature and look into the mechanism underlying gene excision into a mobile genetic element. Results will disclose important information on the distribution of antibiotic resistance elements among humans, animals, food, and the environment.


Integrons are genetic platforms that enhance bacterial evolvability through the acquisition and stockpiling of new genes encoded in mobile elements named cassettes. They are found in the chromosomes of environmental bacteria but some have acquired mobility through their association to transposons and conjugative plasmids. These mobile integrons (MI) caused the unexpected rise of multidrug resistance that is now a major threat to modern medicine, and are good proof of the adaptive power of integrons. Class 1 integrons are the most relevant MI and the major experimental model. Yet little is known about the hundreds of sedentary chromosomal integrons (SCI) that have driven bacterial evolution for eons. The paradigm of SCI is the superintegron (SI), an extremely large integron located in the chromosome of Vibrio cholerae, the causative agent of Cholera disease. Despite its role in the adaptability of one of the deadliest pathogens in history, the SI is poorly characterized because it is only functional in its native genetic background, yet its presence interferes with, and precludes all studies performed in V. cholerae. I propose to solve this paradoxical situation by deleting the SI, an ambitious project not only for its size (126 Kb) but because it is highly stabilized by 17 toxin-antitoxin systems. To do so, I have developed SeqDelTA, a novel method that is already giving excellent preliminary results. I will then use V. cholerae∆SI to study fundamental aspects of SCIs, yet out of reach. I will elucidate the functions encoded in SI cassettes to understand the role and adaptive value of integrons in nature; I will also unravel the genesis of cassettes: how a gene is exapted from its genetic context to become a mobile module; and I will explore the circulation of antibiotic resistance cassettes among humans, animals, food, and the environment with a novel biosynthetic tool (the I3C). KryptonInt will open and explore the historically inaccessible field of study of SCIs.

Host institution

Net EU contribution
€ 1 499 516,00
28040 Madrid

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Comunidad de Madrid Comunidad de Madrid Madrid
Activity type
Higher or Secondary Education Establishments
Total cost
€ 1 499 516,00

Beneficiaries (1)