Le mardi 23 juin 2026, Loïc MEUNIER présentera l'examen en vue de l’obtention du grade académique de Docteur en Sciences (Collège de doctorat en Biochimie, biologie moléculaire et cellulaire, bioinformatique et modélisation) sous la direction de Denis BAURAIN et Philippe JACQUES.

Cette épreuve consistera en la défense publique d’une dissertation intitulée :

« Towards the discovery and evolutionary analysis of Nonribosomal Peptide Synthetases (NRPS) within protist lineages ».

Le Jury sera composé de :

Jury :     M. P. MEYER (Président), Mmes et MM. S. CABOCHE (Institut Pasteur de Lille), D. BAURAIN (Promoteur), P. GEURTS, Ph. JACQUES (Co-promoteur), S. MATTHIJS (ULB), S. RIGALI (Secrétaire).

Abstract

Nonribosomal peptides constitute an important class of secondary metabolites, encompassing a remarkable diversity of structures and biological functions. They are synthesized by nonribosomal peptide synthetases (NRPSs), large multimodular megasynthetases that assemble peptides independently of the ribosomal translation machinery. Bacteria and fungi are among the most prolific organisms encoding NRPSs in their genomes and producing nonribosomal peptides. Meanwhile, protists, a group of eukaryotic organisms composed mainly of unicellular species, are known for their rich repertoire of secondary metabolites, particularly algae and some amoebae. As the presence of NRPSs has not been systematically investigated across protist lineages, we explored their distribution across these lineages to discover and inventory these enzymes. To address this challenge, dedicated bioinformatics tools were developed to automate the annotation of genomes from emerging eukaryotic organisms and the large-scale analysis of genome mining results. Based on these methodologies, a first attempt was made to characterize the peptide backbone of their potential nonribosomal peptide products. Despite their sporadic occurrence, the presence of NRPSs in protists raises intriguing questions regarding their origin and evolutionary history. Do protist NRPSs share a common ancestral origin and have they been vertically inherited throughout eukaryotic evolution? Or were these enzymes acquired through horizontal gene transfer from one or several donor organisms? Similarity networks and phylogenetic trees were used to address these questions and attempt to elucidate the evolutionary scenario underlying their acquisition and propagation.

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