The birth of a bacterial tRNA gene by large-scale, tandem duplication events
Abstract
Organisms differ in the types and numbers of tRNA genes that they carry. While the evolutionary mechanisms behind tRNA gene set evolution have been investigated theoretically and computationally, direct observations of tRNA gene set evolution remain rare. Here, we report the evolution of a tRNA gene set in laboratory populations of the bacterium Pseudomonas fluorescens SBW25. The growth defect caused by deleting the single-copy tRNA gene, serCGA, is rapidly compensated by large-scale (45-290 kb) duplications in the chromosome. Each duplication encompasses a second, compensatory tRNA gene (serTGA) and is associated with a rise in tRNA‑Ser(UGA) in the mature tRNA pool. We postulate that tRNA‑Ser(CGA) elimination increases the translational demand for tRNA‑Ser(UGA), a pressure relieved by increasing serTGA copy number. This work demonstrates that tRNA gene sets can evolve through duplication of existing tRNA genes, a phenomenon that may contribute to the presence of multiple, identical tRNA gene copies within genomes.
Data availability
Illumina whole genome sequencing data has been uploaded to NCBI SRA (accession PRJNA558233). YAMAT-seq data has been uploaded to NCBI GEO (accession GSE144791). Source data files have been provided for Figures 2B, 2C, 2D, 2F, 2G, 2H, 3B, 3C, 3D, 3E, 4C, 4D, 5A, and 5B.
Article and author information
Author details
Funding
Max Planck Society
- Gökçe B Ayan
Max Planck Society
- Hye Jin Park
Max Planck Society
- Jenna Gallie
The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.
Copyright
© 2020, Ayan et al.
This article is distributed under the terms of the Creative Commons Attribution License permitting unrestricted use and redistribution provided that the original author and source are credited.
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