ArticleProceedings of the National Academy of Sciences of the United States of America2013
Mechanism for nitrogen isotope fractionation during ammonium assimilation by Escherichia coli K12.
Article in Proceedings of the National Academy of Sciences of the United States of America, 2013. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Cited by 17 papers.
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Who cites it
17 citing papers in PubMed, 44 citations in OpenAlex.
- Nitrogen Isotope Effects in Urea Metabolism: From Biochemistry toInternational journal of molecular sciences · 2026Review
- Ammonia as a parameter shaping habitability on icy moons.FEMS microbes · 2026Review
- Ammonia-Assimilating Bacteria Promote Wheat (Microorganisms · 2024Article
- Nitrogen isotopic composition as a gauge of tumor cell anabolism-to-catabolism ratio.Scientific reports · 2023Article
- Influence of sulfide on diazotrophic growth of the methanogen Methanococcus maripaludis and its implications for the origin of nitrogenase.Communications biology · 2023Article
- The extent of nitrogen isotopic fractionation in rumen bacteria is associated with changes in rumen nitrogen metabolism.PloS one · 2023Article
- Purple sulfur bacteria fix NNature communications · 2021Article
- Distinct nitrogen isotopic compositions of healthy and cancerous tissue in mice brain and head&neck micro-biopsies.BMC cancer · 2021Article
- Nitrite isotope characteristics and associated soil N transformations.Scientific reports · 2021Article
- The origin of N isotopic discrimination and its relationship with feed efficiency in fattening yearling bulls is diet-dependent.PloS one · 2020Article
- Control of the Nitrogen Isotope Composition of the Fungal Biomass: Evidence of Microbial Nitrogen Use Efficiency.Microbes and environments · 2019Article
- Efficient recycling of nutrients in modern and past hypersaline environments.Scientific reports · 2019Article
- KineticScientific reports · 2017Article
- Gene Deletions Resulting in Increased Nitrogen Release by Azotobacter vinelandii: Application of a Novel Nitrogen Biosensor.Applied and environmental microbiology · 2015Article
- Environmental gradients explain species richness and community composition of coastal breeding birds in the Baltic Sea.PloS one · 2015Article
- Intracellular metabolite levels shape sulfur isotope fractionation during microbial sulfate respiration.Proceedings of the National Academy of Sciences of the United States of America · 2014Article
- Nitrogen isotope fractionation by alternative nitrogenases and past ocean anoxia.Proceedings of the National Academy of Sciences of the United States of America · 2014Article
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Authors and funding
4 authors at 2 institutions in 1 country.
Funding
Abstract
Organisms that use ammonium as the sole nitrogen source discriminate between [(15)N] and [(14)N] ammonium. This selectivity leaves an isotopic signature in their biomass that depends on the external concentration of ammonium. To dissect how differences in discrimination arise molecularly, we examined a wild-type (WT) strain of Escherichia coli K12 and mutant strains with lesions affecting ammonium-assimilatory proteins. We used isotope ratio mass spectrometry (MS) to assess the nitrogen isotopic composition of cell material when the strains were grown in batch culture at either high or low external concentrations of NH3 (achieved by controlling total NH4Cl and pH of the medium). At high NH3 (≥ 0.89 µM), discrimination against the heavy isotope by the WT strain (-19.2‰) can be accounted for by the equilibrium isotope effect for dissociation of NH4(+) to NH3 + H(+). NH3 equilibrates across the cytoplasmic membrane, and glutamine synthetase does not manifest an isotope effect in vivo. At low NH3 (≤ 0.18 µM), discrimination reflects an isotope effect for the NH4(+) channel AmtB (-14.1‰). By making E. coli dependent on the low-affinity ammonium-assimilatory pathway, we determined that biosynthetic glutamate dehydrogenase has an inverse isotope effect in vivo (+8.8‰). Likewise, by making unmediated diffusion of NH3 across the cytoplasmic membrane rate-limiting for cell growth in a mutant strain lacking AmtB, we could deduce an in vivo isotope effect for transport of NH3 across the membrane (-10.9‰). The paper presents the raw data from which our conclusions were drawn and discusses the assumptions underlying them.
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Read under generation 80e0d062 · epoch 390. Bibliography from PubMed, PubMed Central and OpenAlex; grants from NIH RePORTER; trial links from ClinicalTrials.gov; estimates, votes and beliefs from the OpenQuestion graph.