Need‐based activation of ammonium uptake in Escherichia coli
Abstract The efficient sequestration of nutrients is vital for the growth and survival of microorganisms. Some nutrients, such as CO2 and NH3, are readily diffusible across the cell membrane. The large membrane permeability of these nutrients obviates the need of transporters when the ambient level...
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| Format: | Article |
| Language: | English |
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Springer Nature
2012-09-01
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| Series: | Molecular Systems Biology |
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| Online Access: | https://doi.org/10.1038/msb.2012.46 |
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| _version_ | 1849331435389845504 |
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| author | Minsu Kim Zhongge Zhang Hiroyuki Okano Dalai Yan Alexander Groisman Terence Hwa |
| author_facet | Minsu Kim Zhongge Zhang Hiroyuki Okano Dalai Yan Alexander Groisman Terence Hwa |
| author_sort | Minsu Kim |
| collection | DOAJ |
| description | Abstract The efficient sequestration of nutrients is vital for the growth and survival of microorganisms. Some nutrients, such as CO2 and NH3, are readily diffusible across the cell membrane. The large membrane permeability of these nutrients obviates the need of transporters when the ambient level is high. When the ambient level is low, however, maintaining a high intracellular nutrient level against passive back diffusion is both challenging and costly. Here, we study the delicate management of ammonium (NH4+/NH3) sequestration by E. coli cells using microfluidic chemostats. We find that as the ambient ammonium concentration is reduced, E. coli cells first maximize their ability to assimilate the gaseous NH3 diffusing into the cytoplasm and then abruptly activate ammonium transport. The onset of transport varies under different growth conditions, but always occurring just as needed to maintain growth. Quantitative modeling of known interactions reveals an integral feedback mechanism by which this need‐based uptake strategy is implemented. This novel strategy ensures that the expensive cost of upholding the internal ammonium concentration against back diffusion is kept at a minimum. |
| format | Article |
| id | doaj-art-2b012ad1639e44fe83508ae581fb712b |
| institution | Kabale University |
| issn | 1744-4292 |
| language | English |
| publishDate | 2012-09-01 |
| publisher | Springer Nature |
| record_format | Article |
| series | Molecular Systems Biology |
| spelling | doaj-art-2b012ad1639e44fe83508ae581fb712b2025-08-20T03:46:37ZengSpringer NatureMolecular Systems Biology1744-42922012-09-018111010.1038/msb.2012.46Need‐based activation of ammonium uptake in Escherichia coliMinsu Kim0Zhongge Zhang1Hiroyuki Okano2Dalai Yan3Alexander Groisman4Terence Hwa5Department of Physics, University of California at San DiegoSection of Molecular Biology, Division of Biological Sciences, University of California at San DiegoDepartment of Physics, University of California at San DiegoDepartment of Microbiology and Immunology, Indiana University School of MedicineDepartment of Physics, University of California at San DiegoDepartment of Physics, University of California at San DiegoAbstract The efficient sequestration of nutrients is vital for the growth and survival of microorganisms. Some nutrients, such as CO2 and NH3, are readily diffusible across the cell membrane. The large membrane permeability of these nutrients obviates the need of transporters when the ambient level is high. When the ambient level is low, however, maintaining a high intracellular nutrient level against passive back diffusion is both challenging and costly. Here, we study the delicate management of ammonium (NH4+/NH3) sequestration by E. coli cells using microfluidic chemostats. We find that as the ambient ammonium concentration is reduced, E. coli cells first maximize their ability to assimilate the gaseous NH3 diffusing into the cytoplasm and then abruptly activate ammonium transport. The onset of transport varies under different growth conditions, but always occurring just as needed to maintain growth. Quantitative modeling of known interactions reveals an integral feedback mechanism by which this need‐based uptake strategy is implemented. This novel strategy ensures that the expensive cost of upholding the internal ammonium concentration against back diffusion is kept at a minimum.https://doi.org/10.1038/msb.2012.46active transportfutile cycleintegral feedbackmetabolic coordinationmicrofluidics |
| spellingShingle | Minsu Kim Zhongge Zhang Hiroyuki Okano Dalai Yan Alexander Groisman Terence Hwa Need‐based activation of ammonium uptake in Escherichia coli Molecular Systems Biology active transport futile cycle integral feedback metabolic coordination microfluidics |
| title | Need‐based activation of ammonium uptake in Escherichia coli |
| title_full | Need‐based activation of ammonium uptake in Escherichia coli |
| title_fullStr | Need‐based activation of ammonium uptake in Escherichia coli |
| title_full_unstemmed | Need‐based activation of ammonium uptake in Escherichia coli |
| title_short | Need‐based activation of ammonium uptake in Escherichia coli |
| title_sort | need based activation of ammonium uptake in escherichia coli |
| topic | active transport futile cycle integral feedback metabolic coordination microfluidics |
| url | https://doi.org/10.1038/msb.2012.46 |
| work_keys_str_mv | AT minsukim needbasedactivationofammoniumuptakeinescherichiacoli AT zhonggezhang needbasedactivationofammoniumuptakeinescherichiacoli AT hiroyukiokano needbasedactivationofammoniumuptakeinescherichiacoli AT dalaiyan needbasedactivationofammoniumuptakeinescherichiacoli AT alexandergroisman needbasedactivationofammoniumuptakeinescherichiacoli AT terencehwa needbasedactivationofammoniumuptakeinescherichiacoli |