Ribosomally synthesized post-translationally modified peptides, or RiPPs, display a tremendous diversity of structures and bio-activities. Most classes of RiPPs are produced by bacteria and mediate antagonistic or cooperative interactions between them or interactions with their environment. We have identified a new class of RiPPs in a large range of bacterial species. Most of them are environmental bacteria, but these RiPPs are also found in some important pathogens. Their core operons comprise genes coding for a RiPP precursor and for modification enzymes of poorly characterized families. These RiPPs display novel features. Their precursors belong to several new families with conserved Cys-rich motifs and are highly variable in sizes. Our first data indicate that this class of RiPPs represents a widespread, yet unknown strategy for defense against copper or other stress affecting proteostasis in bacteria, which is a new function for RiPPs. Copper is a widely used antibacterial agent that is also involved at the host-pathogen interface. Our objective is to characterize the functions, the structures and the biogenesis of these RiPPs by using an integrative approach combining bacteriology, biochemistry and biophysical techniques. We will determine the functions of these RiPPs in a model environmental species, Caulobacter crescentus, and in a model pathogenic species, Bordetella pertussis. We will generate various mutants in those operons and analyze them by using several phenotypic assays. We will purify the mature RiPPs and analyze their interactions with copper using spectroscopic methods. We will characterize the structures and post-translational modifications of these RiPPs using both bottom-up and top-down mass spectrometry approaches, as well as 2D homo- and heteronuclear nuclear magnetic resonance (NMR) methods. We will investigate the specific features of their biogenesis. We will determine the activities of the modification enzymes by reconstituting these systems in vitro. We will also decipher the mode of interaction between the RiPP precursors and the enzymatic complexes that catalyze their post-translational modification. Altogether, these studies will lead to the characterization of a new class of RiPPs involved in bacterial adaptation to specific stressors, notably copper, and which display a number original features.
Madame Françoise Jacob-Dubuisson (IPL-CIIL-Recherche sur les Mycobactéries et les Bordetelles)
The author of this summary is the project coordinator, who is responsible for the content of this summary. The ANR declines any responsibility as for its contents.
IPL-CIIL-RMB IPL-CIIL-Recherche sur les Mycobactéries et les Bordetelles
TBI Institut National des Sciences Appliquées Toulouse
MCAM Muséum National d'Histoire Naturelle Paris
Help of the ANR 367,759 euros
Beginning and duration of the scientific project: September 2022 - 36 Months