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SUMMARY:Crystal structures of bacterial and yeast ribosomes - Marat Yusupo
 v\, Illkirch\, France
DTSTART:20110127T161500Z
DTEND:20110127T180000Z
UID:TALK28466@talks.cam.ac.uk
CONTACT:Scientific Meetings Co-ordinator
DESCRIPTION:The crystal structure of the yeast 80S ribosome determined at 
 4.15 Å resolution reveals the higher complexity of eukaryotic ribosomes\,
  which are 40% larger than their bacterial counterparts. Our crystals capt
 ure the ribosome in the ratcheted state which is essential for translocati
 on of mRNA and tRNA and where the small ribosomal subunit has rotated with
  respect to the large subunit. We describe the conformational changes in b
 oth ribosomal subunits that are involved in ratcheting\, and their implica
 tions to mRNA and tRNA translocation. Structural rearrangements of the rib
 osome in the tRNA binding step have been studied on bacterial ribosome mod
 el.  Discrimination of tRNA on the ribosome occurs in two consecutive step
 s: initial selection and proofreading. We propose a proofreading mechanism
  based on comparison of crystal structures of the 70S ribosome with an emp
 ty A site or the A site occupied by cognate or non-cognate tRNA.  We have 
 shown involvement of tales of ribosomal proteins in stabilization of corre
 ct tRNA on the ribosome. We suggest that proofreading begins with stabiliz
 ation of tRNA anticodon loop with involvement of magnesium ions\, followin
 g by stabilization of elbow region and accommodation of the acceptor end i
 n the peptidyl transferase center.
LOCATION:Max Perutz Lecture Theatre\, Medical Research Council (MRC) (MRC 
 Laboratory of Molecular Biol
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