RT Journal Article SR Electronic T1 On the flexibility of the cellular amination network in E. coli JF bioRxiv FD Cold Spring Harbor Laboratory SP 2022.01.25.477661 DO 10.1101/2022.01.25.477661 A1 Helena Schulz-Mirbach A1 Alexandra Müller A1 Tong Wu A1 Pascal Pfister A1 Selçuk Aslan A1 Lennart Schada von Borzyskowski A1 Tobias J. Erb A1 Arren Bar-Even A1 Steffen N. Lindner YR 2022 UL http://biorxiv.org/content/early/2022/01/27/2022.01.25.477661.abstract AB 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 source 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.