Translation initiation factor IF2 interacts with the 30 S ribosomal subunit via two separate binding sites

被引:54
作者
Caserta, Enrico
Tomsic, Jerneja
Spurio, Roberto
La Teana, Anna
Pon, Cynthia L.
Gualerzi, Claudio O. [1 ]
机构
[1] Univ Camerino, Dept Biol, Genet Lab, I-62032 Camerino, MC, Italy
[2] Politech Univ Marche, Inst Biochem, I-60131 Ancona, Italy
关键词
translation initiation; structure-function relationship; IF2; domains; guanine nucleotides; IF1;
D O I
10.1016/j.jmb.2006.07.043
中图分类号
Q5 [生物化学]; Q7 [分子生物学];
学科分类号
071010 ; 081704 ;
摘要
The functional properties of the two natural forms of Escherichia coli translation initiation factor IF2 (IF2 alpha and IF2 beta) and of an N-terminal deletion mutant of the factor (1F2 Delta N) lacking the first 294 residues, corresponding to the entire N-terminal domain, were analysed comparatively. The results revealed that IF2 alpha and IF2 beta display almost indistinguishable properties, whereas IF2 Delta N, although fully active in all steps of the translation initiation pathway, displays functional activities having properties and requirements distinctly different from those of the intact molecule. Indeed, binding of IF2 Delta N to the 30 S subunit, IF2 Delta N-dependent stimulation of fMet-tRNA binding to the ribosome and of initiation dipeptide formation strongly depend upon the presence of IF1 and GTP, unlike with IF2 alpha and IF2 beta. The present results indicate that, using two separate active sites, IF2 establishes two interactions with the 30S ribosomal subunit which have different properties and functions. The first site, located in the N domain of IF2, is responsible for a high-affinity interaction which "anchors" the factor to the subunit while the second site, mainly located in the beta-barrel module homologous to domain II of EF-G and EF-Tu, is responsible for the functional ("core") interaction of IF2 leading to the decoding of fMet-tRNA in the 30 S subunit P-site. The first interaction is functionally dispensable, sensitive to ionic-strength variations and essentially insensitive to the nature of the guanosine nucleotide ligand and to the presence of IF1, unlike the second interaction which strongly depends upon the presence of IF1 and GTP. (c) 2006 Elsevier Ltd. All rights reserved.
引用
收藏
页码:787 / 799
页数:13
相关论文
共 64 条
[1]   3-DIMENSIONAL STRUCTURE OF THE RIBOSOMAL TRANSLOCASE - ELONGATION-FACTOR-G FROM THERMUS-THERMOPHILUS [J].
AEVARSSON, A ;
BRAZHNIKOV, E ;
GARBER, M ;
ZHELTONOSOVA, J ;
CHIRGADZE, Y ;
AL-KARADAGHI, S ;
SVENSSON, LA ;
LILJAS, A .
EMBO JOURNAL, 1994, 13 (16) :3669-3677
[2]   The structure of elongation factor G in complex with GDP: Conformational flexibility and nucleotide exchange [J].
Al-Karadaghi, S ;
AEvarsson, A ;
Garber, M ;
Zheltonosova, J ;
Liljas, A .
STRUCTURE, 1996, 4 (05) :555-565
[3]   The cryo-EM structure of a translation initiation complex from Escherichia coli [J].
Allen, GS ;
Zavialov, A ;
Gursky, R ;
Ehrenberg, M ;
Frank, J .
CELL, 2005, 121 (05) :703-712
[4]   The roles of initiation factor 2 and guanosine triphosphate in initiation of protein synthesis [J].
Antoun, A ;
Pavlov, MY ;
Andersson, K ;
Tenson, T ;
Ehrenberg, M .
EMBO JOURNAL, 2003, 22 (20) :5593-5601
[5]   Ribosome formation from subunits studied by stopped-flow and Rayleigh light scattering [J].
Antoun A. ;
Pavlov M.Y. ;
Tenson T. ;
Ehrenberg M. .
Biological Procedures Online, 2004, 6 (1) :35-54
[6]   CRYSTAL-STRUCTURE OF ACTIVE ELONGATION-FACTOR TU REVEALS MAJOR DOMAIN REARRANGEMENTS [J].
BERCHTOLD, H ;
RESHETNIKOVA, L ;
REISER, COA ;
SCHIRMER, NK ;
SPRINZL, M ;
HILGENFELD, R .
NATURE, 1993, 365 (6442) :126-132
[7]   Structure and function of bacterial initiation factors [J].
Boelens, R ;
Gualerzi, CO .
CURRENT PROTEIN & PEPTIDE SCIENCE, 2002, 3 (01) :107-119
[8]   Chaperone properties of bacterial elongation factor EF-G and initiation factor IF2 [J].
Caldas, T ;
Laalami, S ;
Richarme, G .
JOURNAL OF BIOLOGICAL CHEMISTRY, 2000, 275 (02) :855-860
[9]   MECHANISM OF TRANSLATIONAL INITIATION IN PROKARYOTES - EVIDENCE FOR A DIRECT EFFECT OF IF2 ON THE ACTIVITY OF THE 30-S RIBOSOMAL-SUBUNIT [J].
CANONACO, MA ;
CALOGERO, RA ;
GUALERZI, CO .
FEBS LETTERS, 1986, 207 (02) :198-204
[10]  
CASHEL M, 1969, J BIOL CHEM, V244, P3133