Etude biochimique, bio-informatique et bio-électrochimique de transcétolases d'intérêt médical et criblage d'inhibiteurs potentiels

Overview & Synopsis

The work of Duchesne and Flemming was confirmed in 1928 with the discovery of penicillin, which revolutionised medicine. With the diversification of antibiotics in the second half of the 20th century, it became possible to eradicate infectious diseases such as cholera and tuberculosis from Europe. However, the progressive antibiotic resistance of bacterial strains, the rarefaction of the pipeline of effective molecules and global warming are calling current healthcare policies into question. By 2050, the best forecasts predict that almost 10 million people will die as a result of antibiotic resistance, as well as the explosion in cases of fungal and parasitic infections such as candidiasis and malaria. In this context, there is an urgent need to identify new molecules that are effective against these infectious agents by targeting new proteins involved in biological functions that are important for the survival of these pathogens. Transketolases are ubiquitous enzymes present in the pentose phosphate pathway, still poorly exploited in medicine, and involved in the regeneration of NADPH and the synthesis of precursors to nucleic acids and aromatic amino acids. This scientific project involves the biochemical, bioinformatic and structural characterisation of eleven transketolases, eight of them are newly expressed. The natural ping-pong mechanism of transketolases is modified into a random sequential mechanism in the presence of ferricyanide. This oxido-reducing molecule is now considered to be a non-natural substrate for these enzymes, capable of interacting with a crown of histidines present at the entrance to their active site. This crown, which has been highly conserved throughout the evolution of transketolases, is involved in major functions such as coenzyme stabilisation and activation, and substrate stabilisation. From a structural point of view, Human transketolase seems sufficiently distant from the transketolases of pathogenic organisms to envisage specifically inhibiting the latter. This last point is supported by the electrochemical screening of a chemical library using a new multiplexed electrochemistry device developed in collaboration between laboratories in Lyon.