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SUMMARY:RNA degradation and polyadenylation in Arabidopsis thaliana - Dr D
 ominique Gagliardi - IBMP\, Strasbourg
DTSTART:20090122T160000Z
DTEND:20090122T170000Z
UID:TALK15801@talks.cam.ac.uk
CONTACT:3901
DESCRIPTION:Polyadenylation is best known for its role in stabilizing polI
 I transcripts and facilitating both mRNA export from the nucleus and trans
 lation initiation. Paradoxically\, the ancestral role of polyadenylation i
 s to tag RNA for degradation by facilitating the recognition of transcript
 s by 3' to 5' exoribonucleases. In fact\, the connection between polyadeny
 lation and RNA degradation is conserved in the three domains of life: Euca
 ryotes\, Bacteria and some Archaea. In plants\, polyadenylation-mediated R
 NA degradation operates in the three genetic compartments: the mitochondri
 on\, the chloroplast and the nucleus. In plant mitochondria and chloroplas
 ts\, polyadenylated RNAs are degraded by polynucleotide phosphorylases (mt
 PNPase and cpPNPase\, respectively). Both cpPNPase and mtPNPase are involv
 ed in mRNA and rRNA degradation/maturation. In addition\, the mtPNPase deg
 rades cryptic transcripts that are abundantly produced in plant mitochondr
 ia as a consequence of complex genome organisation and expression. Polyade
 nylation-mediated RNA degradation by mtPNPase thus plays an essential role
  in establishing the final transcriptome in plant mitochondria. In the nuc
 leus\, polyadenylated RNAs destined for degradation are eliminated by the 
 exosome and one of its co-factors\, Rrp6\, a 3' to 5' exoribonuclease. In 
 Arabidopsis\, rice and poplar\, three genes encode RRP6-like proteins\, wh
 ile in other eukaryotes RRP6 is encoded by a single gene. The three Arabid
 opsis RRP6-like proteins are likely to be functionally specialized as they
  have distinctive localisations. Initial functional characterization impli
 cates RRP6L2 in nuclear polyadenylation-mediated RNA degradation. The role
 s of poly(A)-mediated RNA degradation pathways are just beginning to be un
 raveled in plants. Non-canonical poly(A) polymerases are encoded by small 
 multigene gene families in plants and likely play additional roles in geno
 me expression besides RNA recognition in degradative pathways.\n\nhttp://i
 bmp.u-strasbg.fr/index.php?id=48&L=1
LOCATION:Department of Plant Sciences\, Large Lecture Theatre
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