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Coevolution of the translational machinery optimizes initiation with unusual initiator tRNAs and initiation codons in mycoplasmas

Ayyub, Shreya Ahana and Dobriyal, Divya and Shah, Riyaz Ahmad and Lahrya, Kuldeep and Bhattacharyya, Madhumita and Bhattacharyya, Souvik and Chakrabarti, Saikat and Varshney, Umesh (2018) Coevolution of the translational machinery optimizes initiation with unusual initiator tRNAs and initiation codons in mycoplasmas. In: RNA BIOLOGY, 15 (1). pp. 70-80.

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Official URL: http://dx.doi.org/10.1080/15476286.2017.1377879


Initiator tRNAs (i-tRNAs) are characterized by the presence of three consecutive GC base pairs (GC/GC/GC) in their anticodon stems in all domains of life. However, many mycoplasmas possess unconventional i-tRNAs wherein the highly conserved sequence of GC/GC/GC is represented by AU/GC/GC, GC/GC/GU or AU/GC/GU. These mycoplasmas also tend to preferentially utilize non-AUG initiation codons. To investigate if initiation with the unconventional i-tRNAs and non-AUG codons in mycoplasmas correlated with the changes in the other components of the translation machinery, we carried out multiple sequence alignments of genes encoding initiation factors (IF), 16S rRNAs, and the ribosomal proteins such as uS9, uS12 and uS13. In addition, the occurrence of Shine-Dalgarno sequences in mRNAs was analyzed. We observed that in the mycoplasmas harboring AU/GC/GU i-tRNAs, a highly conserved position of R131 in IF3, is represented by P, F or Y and, the conserved C-terminal tail (SKR) of uS9 is represented by the TKR sequence. Using the Escherichia coli model, we show that the change of R131 in IF3 optimizes initiation with the AU/GC/GU i-tRNAs. Also, the SKR to TKR change in uS9 was compatible with the R131P variation in IF3 for initiation with the AU/GC/GU i-tRNA variant. Interestingly, the mycoplasmas harboring AU/GC/GU i-tRNAs are also human pathogens. We propose that these mycoplasmas might have evolved a relaxed translational apparatus to adapt to the environment they encounter in the host.

Item Type: Journal Article
Publication: RNA BIOLOGY
Additional Information: Copy right for this article belong to TAYLOR & FRANCIS INC, 530 WALNUT STREET, STE 850, PHILADELPHIA, PA 19106 USA
Department/Centre: Division of Biological Sciences > Microbiology & Cell Biology
Date Deposited: 07 May 2018 19:01
Last Modified: 07 May 2018 19:01
URI: http://eprints.iisc.ac.in/id/eprint/59780

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