NcRNA represent most of primary transcripts RNA in higher eukaryotes and tune gene expression via diverse mechanisms. They adopt 3D structures composed at 70% by WC bp forming A-form helices linked by RNA motifs. We identified the pk-turn, a new RNA motif related to k-turns that allow for the formation of a bend of 60° between stems P16 and P17 from the bacterial RNaseP. Yet it features different sequence and structural requirements than k-turns. The 2nd ribozyme which got my attention is the LCrz inserted in GIR2, a group I intron. This twintron is observed in the pre-rRNA 18S of the small subunit of the eukaryoteD. iris. LCrz catalyzes a reaction equivalent to the first step of splicing by group II introns, but in a structural context related to group I introns. We solved the 2.5 Å crystal structure of the LCrz and confirmed the unexpected shape by means of SAXS experiments. This work emphasizes the relationship between structure and function in the evolution of ribozymes.
| Identifer | oai:union.ndltd.org:CCSD/oai:tel.archives-ouvertes.fr:tel-01063838 |
| Date | 13 September 2013 |
| Creators | Meyer, Mélanie |
| Publisher | Université de Strasbourg |
| Source Sets | CCSD theses-EN-ligne, France |
| Language | English |
| Detected Language | English |
| Type | PhD thesis |
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