Systematic evolution of initiation factor 3 and the ribosomal protein uS12 optimizes Escherichia coli growth with an unconventional initiator tRNA

Datta, M and Singh, J and Modak, MJ and Pillai, M and Varshney, U (2022) Systematic evolution of initiation factor 3 and the ribosomal protein uS12 optimizes Escherichia coli growth with an unconventional initiator tRNA. In: Molecular Microbiology, 117 (2). pp. 462-479.

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Abstract

The anticodon stem of initiator tRNA (i-tRNA) possesses the characteristic three consecutive GC base pairs (G29:C41, G30:C40, and G31:C39 abbreviated as GC/GC/GC or 3GC pairs) crucial to commencing translation. To understand the importance of this highly conserved element, we isolated two fast-growing suppressors of Escherichia coli sustained solely on an unconventional i-tRNA (i-tRNAcg/GC/cg) having cg/GC/cg sequence instead of the conventional GC/GC/GC. Both suppressors have the common mutation of V93A in initiation factor 3 (IF3), and additional mutations of either V32L (Sup-1) or H76L (Sup-2) in small subunit ribosomal protein 12 (uS12). The V93A mutation in IF3 was necessary for relaxed fidelity of i-tRNA selection to sustain on i-tRNAcg/GC/cg though with a retarded growth. Subsequent mutations in uS12 salvaged the retarded growth by enhancing the fidelity of translation. The H76L mutation in uS12 showed better fidelity of i-tRNA selection. However, the V32L mutation compensated for the deficient fidelity of i-tRNA selection by ensuring an efficient fidelity check by ribosome recycling factor (RRF). We reveal unique genetic networks between uS12, IF3 and i-tRNA in initiation and between uS12, elongation factor-G (EF-G), RRF, and Pth (peptidyl-tRNA hydrolase) which, taken together, govern the fidelity of translation in bacteria. © 2021 John Wiley & Sons Ltd

Item Type:	Journal Article
Publication:	Molecular Microbiology
Publisher:	John Wiley and Sons Inc
Additional Information:	The copyright for this article belongs to John Wiley and Sons Inc.
Department/Centre:	Division of Biological Sciences > Microbiology & Cell Biology
Date Deposited:	07 Jan 2022 10:41
Last Modified:	11 Sep 2022 06:01
URI:	https://eprints.iisc.ac.in/id/eprint/70951

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