Ammonium (NH4+) is essential to generate the nitrogenous building blocks of life. It gets assimilated via the canonical biosynthetic routes to glutamate and is further distributed throughout metabolism via a network of transaminases. To study the flexibility of this network, we constructed an Escherichia coli glutamate auxotrophic strain. This strain allowed us to systematically study which amino acids serve as amine sources and found that several amino acids complement the auxotrophy, either by producing glutamate via transamination reactions or by their conversion to glutamate. In this network, we identified aspartate transaminase AspC as a major connector between many amino acids and glutamate. Additionally, we extended the transaminase network by the amino acids β-alanine, alanine, glycine, and serine as new amine sources and identified d-amino acid dehydrogenase (DadA) as an intracellular amino acid sink removing substrates from transaminase reactions. Finally, ammonium assimilation routes producing aspartate or leucine were introduced. Our study reveals the high flexibility of the cellular amination network, both in terms of transaminase promiscuity and adaptability to new connections and ammonium entry points.
sequencing data has been deposited at Dryad
Data from: On the flexibility of the cellular amination network in E. coliDryad Digital Repository, doi:10.5061/dryad.mcvdnck2s.
- Steffen N Lindner
- Tobias J Erb
- Helena Schulz-Mirbach
- Alexandra Müller
- Tong Wu
- Selçuk Aslan
- Arren Bar-Even
- Steffen N Lindner
- Pascal Pfister
The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.
- Ahmad S Khalil, Boston University, United States
© 2022, Schulz-Mirbach 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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