Enzyme engineering and evolution
Enzymes are the molecular workers of life. These biocatalysts perform all the chemical reactions inside and outside the cell with extremely high precision and efficacy, most of them also equipped with control mechanisms for speeding up or slowing down their activity as a mean to adapt their function to the environment. Our research is focused on investigating the biochemical mechanisms underlying these remarkable properties of enzymes as well as the molecular mechanisms of evolution that led to their emergence and optimisation over time.
To this aim, we combine modern biotechnology with classical biochemistry for engineering enzyme variants, studying their properties and comparing them with those of the wild type enzyme. We also develop strategies for artificially evolving enzymes in the lab by mimicking the Darwinian principle of mutations and selection. This is called « accelerated evolution » since our lab timescale is much shorter (months to years) than nature’s timescale (millions of years), or « directed evolution » since only a single component of a living organism (in our case an enzyme) will be subjected to an evolutionary process. In practice, we use mutagenesis techniques for creating large libraries of enzyme variants that will be expressed in bacteria (one bacterium express one variant). Such libraries can contain up to a billion different bacteria. Then, the enzyme variants endowed with the property we are looking for will confer a survival advantage to their bacterial host, and these bacteria will be progressively enriched in the population. Finally, the best-fitted bacteria are isolated and the evolved enzyme variants are identified and characterized.
Cyclic peptides and inteins
Besides enzymes, our team is also interested in engineering smaller peptide molecules with the aim of discovering new drugs or new bioactive compounds. We developed a strategy for biosynthesizing cyclic peptides inside microorganisms such as bacteria or yeast. Cyclization, performed by a small protein called an intein, makes the peptide more stable and a better candidate for potential therapeutic use. Using similar directed evolution strategies as for enzymes, we create large libraries of microorganisms expressing peptides and develop selection or screening methods for identifying interesting peptides in these libraries.
