Séminaire de Christophe PENNO (University College Cork)


Le mardi 3 avril 2018 à 12h30, salle de conférences de l'OSUR, bâtiment 14b, Campus de Beaulieu, UR1

Le mardi 3 avril 2018 à 12h30, salle de conférences de l'OSUR, bâtiment 14b, Campus de Beaulieu, UR1

Expansion of the genetic information by Programmed Transcriptional Realignment

Productive utilization of RNA polymerase slippage has been selected to enrich gene expression; such slippage involves realignment with respect to its template of the 3’ end of the product RNA and so is known as Programmed Transcriptional Realignment (PTR). The slippage generally occurs at a slippage-prone site and leads to site-specific product RNA heterogeneity involving either addition or omission of bases(s).  Depending on the location of stop codons, standard translation of such transcripts can yield protein products without or with new frame encoded C-terminal amino acids.  

While a counterpart mechanism at the translational is well known to utilize various sites and stimulators, few are known for PTR. It is only in the past 15 years that a few, but important instances of PTR utilization have been discovered. Such cases include the expression of components of the type III secretion system in Shigella flexneri, the causative agent of the human bacillary dysentery. The most common of the limited number of slippage-prone sites known involve homopolymeric runs of A’s or T’s that are adequate on their own to promote PTR.

Our work has identified the first ‘structural’ PTR stimulator. It is an RNA stem-loop structure specified by a retrotransposon gene of the bacteria, Roseiflexus. The accompanying slippage motif is T5C5 motif. In vitro experiments showed that the (prokaryotic) E. coli and (eukaryotic) S. cerevisiae RNA polymerases are stimulated to slip by the RNA stem-loop stimulator when transcribing the T5C5 motif. Our finding has led to computational and experimental testing of PTR gene candidates in various organisms.

Contact : Christophe PENNO

Seminaires 3 Avril 2018

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