Rescue of Escherichia coli auxotrophy by de novo small proteins
Increasing numbers of small proteins with diverse physiological roles are being identified and characterized in both prokaryotic and eukaryotic systems, but the origins and evolution of these proteins remain unclear. Recent genomic sequence analyses in several organisms suggest that new functions encoded by small open reading frames (sORFs) may emerge de novo from noncoding sequences. However, experimental data demonstrating if and how randomly generated sORFs can confer beneficial effects to cells are limited. Here we show that by up-regulating hisB expression, de novo small proteins (≤ 50 amino acids in length) selected from random sequence libraries can rescue Escherichia coli cells that lack the conditionally essential SerB enzyme. The recovered small proteins are hydrophobic and confer their rescue effect by binding to the 5' end regulatory region of the his operon mRNA, suggesting that protein binding promotes structural rearrangements of the RNA that allow increased hisB expression. This study adds RNA regulatory elements as another interacting partner for de novo proteins isolated from random sequence libraries, and provides further experimental evidence that small proteins with selective benefits can originate from the expression of nonfunctional sequences.
All data generated or analysed during this study are included in the manuscript and supporting file. The mass spectrometry proteomics data have been deposited to the ProteomeXchange Consortium (http://proteomecentral.proteomexchange.org) via the PRIDE partner repository (Perez-Riverol et al. 2019) with the dataset identifier PXD014049.
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Knut och Alice Wallenbergs Stiftelse (2015.0069)
- Dan I Andersson
- Dan I Andersson
- Michael Knopp
- Per Jemth
Knut och Alice Wallenbergs Stiftelse (2017.0071)
- Mårten Larsson
The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.
- Joseph T Wade, New York State Department of Health, United States
- Received: March 1, 2022
- Accepted: March 14, 2023
- Accepted Manuscript published: March 15, 2023 (version 1)
© 2023, Babina 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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