Thesis defence of Emilie Chagny Friday 6 December 14:00 PM Amphi PNBI

Phylogenetic and biochemical insights into the diversity of TET peptidases in Archaea

Come along to Emilie Chagny's thesis defence, scheduled for Friday 6 December in the PNBI amphitheatre

TET peptidases are giant aminopeptidases ubiquitous accross all domains life, proposed to be involved in intracellular proteolysis, acting downstream of the proteasome. Structural studies have shown that these enzymes form hollow dodecameric tetrahedral complexes. In Archaea, TET peptidases have primarily been studied in Thermococcales species, revealing four distinct types of TETs. However, the prevalence and functional diversity of these peptidases in other archaeal lineages remain poorly understood, and their precise biological role is still unclear. In this work, structure-based identification criteria are introduced, enabling highthroughput screening for TETs. By applying these criteria to 4,016 archaeal genomes, the first comprehensive analysis of TET distribution in Archaea was conducted, uncovering an unsuspected diversity. Through phylogenetic analysis, a classification of archaeal TETs in eleven families is proposed. Biochemical characterization of six new enzymes from previously undescribed families and covering a wide taxonomic range of archaeal species offers an extensive overview of the functional diversity of TETs. Finally, by combining biochemical and phylogenetic data, the evolutionary history of these peptidases is addressed, offering new insights into their potential biological roles.