Mechanism of recycling of post-termination ribosomal complexes in eubacteria: A new role of initiation factor 3 |
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Authors: | Anuradha Seshadri Umesh Varshney |
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Institution: | (1) Department of Microbiology and Cell Biology, Indian Institute of Science, 560 012 Bangalore, India |
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Abstract: | Ribosome recycling is a process which dissociates the post-termination complexes (post-TC) consisting of mRNA-bound ribosomes
harbouring deacylated tRNA(s). Ribosome recycling factor (RRF), and elongation factor G (EFG) participate in this crucial
process to free the ribosomal subunits for a new round of translation. We discuss the overall pathway of ribosome recycling
in eubacteria with especial reference to the important role of the initiation factor 3 (IF3) in this process. Depending on
the step(s) at which IF3 function is implicated, three models have been proposed. In model 1, RRF and EFG dissociate the post-TCs
into the 50S and 30S subunits, mRNAand tRNA(s). In this model, IF3, which binds to the 30S subunit, merely keeps the dissociated
subunits apart by its anti-association activity. In model 2, RRF and EFG separate the 50S subunit from the post-TC. IF3 then
dissociates the remaining complex of mRNA, tRNA and the 30S subunit, and keeps the ribosomal subunits apart from each other.
However, in model 3, both the genetic and biochemical evidence support a more active role for IF3 even at the step of dissociation
of the post-TC by RRF and EFG into the 50S and 30S subunits. |
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Keywords: | EFG IF3 post-TC protein synthesis RF specific interactions |
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