About
SEMINAR DEPT MICROBIOLOGY
Friday, November 18th 2022 at 11:30 am
Auditorium Centre François Jacob
Malcolm White
University of St Andrews, Scotland
Invited by Simonetta Gribaldo
(simonetta.gribaldo@pasteur.fr)
“Cyclic nucleotide signaling in prokaryotic immune defence”
Abstract:
Prokaryotic cells uses a diverse array of cyclic nucleotide second messengers to coordinate defence against invading mobile genetic elements (MGE). Type III CRISPR systems detect foreign RNA and generate cyclic oligoadenylate (cOA) second messengers that activate powerful degradative nucleases, while CBASS (Cyclic nucleotide based antiphage signalling systems) make a wide range of cyclic di- and tri-nucleotides that frequently activate abortive infection (cell death) pathways. This talk will focus on the mechanisms of cyclic-nucleotide signalling in anti-viral defence, focussing on two examples under study in our lab. The first is a prophage-encoded type III CRISPR system from Vibrio cholerae that generates a cyclic triadenylate (cA3) signal, activating a powerful NucC DNA endonuclease effector. The second is a bacterial CBASS defence pathway that also functions via a cA3 second messenger, which activates an effector with an enzymatic TIR domain for degradation of cellular NAD+. This CBASS defence involves the assembly of a highly unusual and visually striking effector complex structure. The two pathways can be “mixed and matched” and most likely both operate via abortive infection, highlighting the conserved paradigms for cyclic nucleotide based prokaryotic defence systems.
Location
Room: AUDITORIUM CENTRE FRANCOIS JACOB
Address: Institut Pasteur, Rue du Docteur Roux, Paris, France