Impact of rRNA methylations on ribosome recycling and fidelity of initiation in Escherichia coli

Seshadri, A and Dubey, B and Weber, MHW and Varshney, U (2009) Impact of rRNA methylations on ribosome recycling and fidelity of initiation in Escherichia coli. In: Molecular Microbiology, 72 (3). pp. 795-808.

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Abstract

Ribosomal RNA (rRNA) contains a number of modified nucleosides in functionally important regions including the intersubunit bridge regions. As the activity of ribosome recycling factor (RRF) in separating the large and the small subunits of the ribosome involves disruption of intersubunit bridges, we investigated the impact of rRNA methylations on ribosome recycling. We show that deficiency of rRNA methylations, especially at positions 1518 and 1519 of 16S rRNA near the interface with the 50S subunit and in the vicinity of the IF3 binding site, adversely affects the efficiency of RRF-mediated ribosome recycling. In addition, we show that a compromise in the RRF activity affords increased initiation with a mutant tRNA(fMet) wherein the three consecutive G-C base pairs ((29)GGG(31):39CCC41), a highly conserved feature of the initiator tRNAs, were mutated to those found in the elongator tRNA(Met) ((29)UCA(31):(39)psi GA(41)). This observation has allowed us to uncover a new role of RRF as a factor that contributes to fidelity of initiator tRNA selection on the ribosome. We discuss these and earlier findings to propose that RRF plays a crucial role during all the steps of protein synthesis.

Item Type:	Journal Article
Publication:	Molecular Microbiology
Publisher:	Blackwell Publishing
Additional Information:	Copyrights of this article belongs to Blackwell Publishing.
Keywords:	Peptidyl-Transfer-Rna; Messenger-Rna;Translation Initiation; Protein-Synthesis;70s Ribosome;Factor Rrf; Methyltransferase; Codon;Mutant;Gene.
Department/Centre:	Division of Biological Sciences > Microbiology & Cell Biology
Date Deposited:	17 Aug 2009 08:20
Last Modified:	19 Sep 2010 05:31
URI:	http://eprints.iisc.ac.in/id/eprint/20034

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