Lundi 4 Février 2019
EN SALLE 64
His title is: "Dhr1, an helicase involved in ribosome biogenesis"
Overview: Ribosome biogenesis is a highly complex process in eukaryotes which undergoes through a cascade of structural recognition of many macromolecules. It not only includes ribosomal proteins and RNA. Indeed non ribosomal proteins (nearly 200!) and small nucleolar RNA (snoRNAs) are the key modulators of this dynamic event. Many helicases have been found to be responsible for the reorganization of secondary structures of rRNA as well as dissociation of snoRNAs during the maturation process. In budding yeast, there are more than 20 RNA helicases involved in ribosome assembly, among which DEAH-box Dhr1 is essential due to its obligatory role in the formation of central pseudoknot (CPK) by displacing the box C/D snoRNA U3 from the pre-rRNAs. I will present structural and functional studies of the helicase module of Dhr1, revealing the presence of an atypical carboxyl terminal domain (CTD), involved in the dynamic recruitment to precursor ribosomes. I will discuss the effect of a few mutations (leading to microcephaly and other neurological diseases in human) on Dhr1 function in ribosomal biogenesis and I will present a model for Dhr1-mediated release of U3 snoRNA.