Mechanism of translational initiation in prokaryotes

FEBS Letters

Canonaco, Maria A.²  Calogero, Raffaele A.²  Gualerzi, Claudio O.¹ 

[1] Department of Cell Biology, Laboratory of Genetics, University of Camerino, I-62032 Camerino (MC), Italy;Max-Planck-Institut für Molekulare Genetik, Abteilung Wittmann, D-1000 Berlin 33, Germany

关键词: Protein synthesis;    Initiation factor;    Aminoacyl-tRNA binding;    Ribosome;   

DOI  :  10.1016/0014-5793(86)81488-0

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

Initiation factor IF2 from either Escherichia coli or Bacillus stearothermophilus was found to possess the previously undetected property of stimulating the template-dependent ribosomal binding of aminoacyl-tRNAs with free α-NH₂ groups. IF1, which had no detectable activity alone, was found to stimulate the activity of E. coli IF2 and, to a lesser extent, that of B. stearothermophilus IF2. Since in the absence of ribosomes not even a weak interaction between the two IF2 molecules and the aminoacyl-tRNAs was detected, the present findings indicate that IF2 can act at the ribosomal level stimulating aminoacyl-tRNA binding without prior formation of a binary complex with the aminoacyl-tRNA. IF2 does not appear to open or strengthen a weak A-site binding, but rather to enhance aminoacyl-tRNA binding to a 30 S site equivalent to the P-site by slowing down the rate of aminoacyl-tRNA dissociation from ribosomes.

【 授权许可】

Unknown