Robin Evans

Graduate Student

Center for Structural Biology
Department of Molecular Biophysics & Biochemistry
Yale University
266 Whitney Avenue, 421 Bass Center
New Haven, CT 06520-8114

Phone:  (203) 432-5625
FAX:  (203) 432-3282

Email: robin.evans {at} yale.edu

Structural Studies of the 70S translocation complex

Summary:

Ribosomes catalyze the synthesis of proteins in three key steps: initiation, elongation, and termination. During the elongation cycle of protein synthesis, amino acids are added to the nascent protein in a stepwise manner. Translocation is the final step of the protein elongation cycle during which time the deacylated tRNA moves from the P site to the E site, peptidyl tRNA moves from the A site to the P site and the mRNA progresses forward by three nucleotides in the 3’ direction. Elongation Factor G (EF-G), a member of GTPase family, promotes the translocation of the tRNAs from their pre- to their posttranslocation states. Translocation is a complex process involving a number of steps including conformational changes of both EF-G and the ribosome. The mechanism of translocation has been studied by both biochemistry and electron microscopy but there are still many unanswered questions. To gain a better understanding of the mechanism of translocation it must be characterized at the atomic level. I propose to use X-ray crystallography to further characterize the steps of translocation. Crystal structures of different steps of translocation will reveal molecular contacts between EF-G and the ribosome as well provide a detailed view of the conformational changes that occur during translocation.

EFG Complexes from Cryo EM studies. Figure taken from Rodnina et. al (4).

References:

1. K.S. Wilson, R. Nechifor, J. Mol. Bio 337, 15-30 (2004).

2. H. Stark, M. Rodnina, H. Wieden, M. Heel, W. Wintermeyer, Cell 100, 301-309 (2000).

3. M. Valle, A. Zavialov, J. Sengupta, U. Rawat, M. Ehrenberg, J. Frank, Cell 114, 123-134 (2003).

4. M. Rodnina, H. Stark, A. Savelsbergh, H. Wieden, D. Mohr, N. Matassova, F. Peske, T. Daviter, C. Gualerzi, W. Wintermeyer, Biol. Chem 381, 377-387 (2000).

5. K. Wilson, H.F. Noller, Cell 92, 337-349 (1998).

6. M. Rodnina, A. Savelsbergh, V. Katunin, W. Wintermeyer, Nature 385, 37-41 (1997).