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  current news   Press   selected story    
     
  9th June 2009  
 

Structural insights into eRF3 and stop codon recognition by eRF1

 
 




Authors
Zhihong Cheng, Kazuki Saito, Andrey V. Pisarev, Miki Wada, Vera P. Pisareva, Tatyana V. Pestova, Michal Gajda, Adam Round, Chunguang Kong, Mengkiat Lim, Yoshikazu Nakamura, Dmitri I. Svergun, Koichi Ito, and Haiwei Song

Abstract
Eukaryotic translation termination is mediated by two interacting release factors, eRF1 and eRF3, which act cooperatively to ensure efficient stop codon recognition and fast polypeptide release. The crystal structures of human and Schizosaccharomyces pombe full-length eRF1 in complex with eRF3 lacking the GTPase domain revealed details of the interaction between these two factors and marked conformational changes in eRF1 that occur upon binding to eRF3, leading eRF1 to resemble a tRNA molecule. Small-angle X-ray scattering analysis of the eRF1/eRF3/GTP complex suggested that eRF1ís M domain contacts eRF3ís GTPase domain. Consistently, mutation of Arg192, which is predicted to come in close contact with the switch regions of eRF3, revealed its important role for eRF1ís stimulatory effect on eRF3ís GTPase activity. An ATP molecule used as a crystallization additive was bound in eRF1ís putative decoding area. Mutational analysis of the ATP-binding site shed light on the mechanism of stop codon recognition by eRF1.

 
 


 
 

 

Figure legend. Structural comparison of the eRF1/eRF3-23 complexes with EF-Tu–GTP–tRNA, and the modeled eRF1/eRF3/GTP complex. (A) Relocation of the GGQ motif in domain M of eRF1 upon binding to eRF3. The GGQ motif is shown in sphere. Domains N andMof eRF1 in form I and in free state are shown in limegreen and lemon, respectively. (B) Structural comparison of eRF1 in form I with tRNA in the EFTu–GTP–tRNA complex. Both are shown in solid deep-olive surface model. (C,D) Superposition of the HeRF1/eRF3-23 complex (C) and the SpeRF1/eRF3-23 complex (D) with the EFTu– GTP–tRNA complex. The ribbon diagrams are generated by superposition of domains 2 and 3 of eRF3 with those of EF-Tu. The tRNA is shown in orange, EF-Tu in green, and the human and S. pombe eRF1/eRF3-23 complexes in magenta and salmon, respectively.
The switch I and switch II regions of EF-Tu are shown in yellow and red, respectively, Mg2+ ion in blue sphere, and GTP in stick model. (E) The model of the eRF1/eRF3/GTP complex. G domain and domains 2 and 3 of eRF3 are colored in gray and wheat, respectively.
The coloring scheme for the final modeled eRF1 is the same as in Figure 1. Superimposed domains M and
N of eRF1 in the human complex as a rigid body with domain N of eRF1 in the S. pombe complex is shown in light pink. Arg192 and Arg203 in human eRF1 are shown in stick models. (F) Crystal structure of Cdc42/ RhoGDI. Cdc42 is shown in gray. The regulatory arm of RhoGDI is shown in green and the rest of the molecule in cyan, Mg2+ ion in blue sphere, and switches I and II in yellow and red.

Published online on May 1 2009 doi:10.1101/gad.1770109
in Genes & Development 23: 1106-1118

For more information on Song HaiWei’s Lab, Please Click here.