RidA proteins contribute to fitness of S. enterica and E. coli by reducing 2AA stress and moderating flux to isoleucine biosynthesis
Authors:Ronnie L. Fulton, Bryce R. Sawyer and Diana M Downs
Department of Microbiology, University of Georgia, Athens, GA 30602-2605.
Keywords:
RidA, 2-aminoacrylate, competitive fitness, metabolic stress.
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Conflict of interest statement:
The authors declare no conflicts of interest.
Please cite this article as:
Ronnie L. Fulton, Bryce R. Sawyer, Diana M Downs (2024). RidA proteins contribute to fitness of S. enterica and E. coli by reducing 2AA stress and moderating flux to isoleucine biosynthesis. Microbial Cell 11: 339-352. doi: 10.15698/mic2024.10.837
© 2024 Fulton et al. This is an open-access article released under the terms of the Creative Commons Attribution (CC BY) license, which allows the unrestricted use, distribution, and reproduction in any medium, provided the original author and source are acknowledged.
Abstract:
Defining the physiological role of a gene product relies on interpreting phenotypes caused by the lack, or alteration, of the respective gene product. Mutations in critical genes often lead to easily recognized phenotypes that can include changes in cellular growth, metabolism, structure etc. However, mutations in many important genes may fail to generate an obvious defect unless additional perturbations are caused by medium or genetic background. The latter scenario is exemplified by RidA proteins. In vitro RidA proteins deaminate numerous imine/enamines, including those generated by serine/threonine dehydratase IlvA (EC:4.3.1.19) from serine or threonine – 2-aminoacrylate (2AA) and 2- aminocrotonate (2AC), respectively. Despite this demonstrable biochemical activity, a lack of RidA has little to no effect on growth of E. coli or S. enterica without the application of additional metabolic perturbation. A cellular role of RidA is to prevent accumulation of 2AA which, if allowed to persist, can irreversibly damage pyridoxal 5’-phosphate (PLP)-dependent enzymes, causing global metabolic stress. Because the phenotypes caused by a lack of RidA are dependent on the unique structure of each metabolic network, the link between RidA function and 2AA stress is difficult to demonstrate in some organisms. The current study used coculture experiments to exacerbate differences in growth caused by the lack of RidA in S. enterica and E. coli. Results described here solidify the established role of RidA in removing 2AA, while also presenting evidence for a role of RidA in enhancing flux towards isoleucine biosynthesis in E. coli. Overall, these data emphasize that metabolic networks can generate distinct responses to perturbation, even when the individual components are conserved.
doi: 10.15698/mic2024.10.837
Volume 11, pp. 339 to 352, published 04/10/2024.