Journal article
Metabolic control of nitrogen fixation in rhizobium-legume symbioses
- Abstract:
- Rhizobia induce nodule formation on legume roots and differentiate into bacteroids, which catabolize plant-derived dicarboxylates to reduce atmospheric N2 into ammonia. Despite the agricultural importance of this symbiosis, the mechanisms that govern carbon and nitrogen allocation in bacteroids and promote ammonia secretion to the plant are largely unknown. Using a metabolic model derived from genome-scale datasets, we show that carbon polymer synthesis and alanine secretion by bacteroids facilitate redox balance in microaerobic nodules. Catabolism of dicarboxylates induces not only a higher oxygen demand but also a higher NADH/NAD+ ratio than sugars. Modeling and 13C metabolic flux analysis indicate that oxygen limitation restricts the decarboxylating arm of the tricarboxylic acid cycle, which limits ammonia assimilation into glutamate. By tightly controlling oxygen supply and providing dicarboxylates as the energy and electron source donors for N2 fixation, legumes promote ammonia secretion by bacteroids. This is a defining feature of rhizobium-legume symbioses.
- Publication status:
- Published
- Peer review status:
- Peer reviewed
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(Preview, Version of record, 541.2KB, Terms of use)
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- Publisher copy:
- 10.1126/sciadv.abh2433
Authors
+ Engineering and Physical Sciences Research Council
More from this funder
- Funder identifier:
- http://dx.doi.org/10.13039/501100000266
- Grant:
- EP/M002454/1
+ Natural Environment Research Council
More from this funder
- Funder identifier:
- http://dx.doi.org/10.13039/501100000270
- Grant:
- NE/L501530/1
+ Biotechnology and Biological Sciences Research Council
More from this funder
- Funder identifier:
- http://dx.doi.org/10.13039/501100000268
- Grant:
- BB/F013159/1
- BB/M011224
- Publisher:
- American Association for the Advancement of Science
- Journal:
- Science Advances More from this journal
- Volume:
- 7
- Issue:
- 31
- Article number:
- eabh2433
- Publication date:
- 2021-07-30
- Acceptance date:
- 2021-06-14
- DOI:
- EISSN:
-
2375-2548
- Language:
-
English
- Keywords:
- Pubs id:
-
1182048
- Local pid:
-
pubs:1182048
- Deposit date:
-
2021-06-15
Terms of use
- Copyright holder:
- Schulte et al.
- Copyright date:
- 2021
- Rights statement:
- Copyright © 2021 The Authors, some rights reserved; exclusive licensee American Association for the Advancement of Science. No claim to original U.S. Government Works. Distributed under a Creative Commons Attribution License 4.0 (CC BY). https://creativecommons.org/licenses/by/4.0/ This is an open-access article distributed under the terms of the Creative Commons Attribution license, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
- Licence:
- CC Attribution (CC BY)
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