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08:25
Measuring Nitrite and Nitrate, Metabolites in the Nitric Oxide Pathway, in Biological Materials using the Chemiluminescence Method
Published on: December 25, 2016
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How Chlamydomonas handles nitrate and the nitric oxide cycle
Victoria Calatrava1, Alejandro Chamizo-Ampudia1, Emanuel Sanz-Luque1
1Departamento de Bioquímica y Biología Molecular, Campus de Rabanales y Campus Internacional de Excelencia Agroalimentario (CeiA3), Edif. Severo Ochoa, Universidad de Córdoba, Spain.
Journal of Experimental Botany
|February 16, 2017
Summary
Nitrate reductase (NR) in Chlamydomonas plays a dual role, facilitating nitrate assimilation and regulating the nitric oxide (NO) cycle. This NO signaling pathway modulates nitrate uptake and assimilation, highlighting NR
Area of Science:
- Plant molecular biology
- Nitrogen metabolism
- Algal physiology
Background:
- Chlamydomonas serves as a model organism for studying nitrogen assimilation.
- Nitrate (NO3-) is crucial as both a nutrient source and signaling molecule in plants.
- Efficient nitrate assimilation requires transporters, nitrate reductase (NR), nitrite reductase (NiR), and GS/GOGAT enzymes.
Purpose of the Study:
- To review the multifaceted role of nitrate reductase (NR) in Chlamydomonas.
- To elucidate the involvement of NR in the nitric oxide (NO) cycle.
- To understand how NO acts as a signaling molecule in nitrate assimilation.
Main Methods:
- Literature review focusing on nitrate assimilation and NO signaling pathways.
- Analysis of the enzymatic functions of NR, ARC/NOFNiR, and THB1.
- Examination of gene regulation mediated by the NIT2 transcription factor.
Main Results:
- Nitrate reductase (NR) facilitates the conversion of nitrite (NO2-) to nitric oxide (NO) using ARC/NOFNiR.
- Truncated haemoglobin THB1 aids NR in converting nitric oxide (NO) back to nitrate (NO3-).
- Nitric oxide (NO) acts as a negative signal, inhibiting nitrate transporters and NR activity/expression.
Conclusions:
- Nitrate reductase (NR) is a key regulator in the NO cycle, transforming nitrate's positive signal into NO's negative signal.
- The NO cycle, involving NR, mediates feedback regulation of nitrate assimilation.
- NR's role extends beyond assimilation to strategic regulation of NO signaling in Chlamydomonas.
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