N-Acetyl-L-glutamate Kinase of Chlamydomonas reinhardtii: In Vivo Regulation by PII Protein and Beyond

N-Acetyl-L-glutamate kinase (NAGK) catalyzes the rate-limiting step in the ornithine/arginine biosynthesis pathway in eukaryotic and bacterial oxygenic phototrophs. NAGK is the most highly conserved target of the PII signal transduction protein in Cyanobacteria and Archaeplastida (red algae and Chlo...

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Bibliographic Details
Published in:International journal of molecular sciences 2023-08, Vol.24 (16), p.12873
Main Authors: Vlasova, Vitalina, Lapina, Tatiana, Statinov, Vladislav, Ermilova, Elena
Format: Article
Language:English
Subjects:
Algae
Amino acids
arginine biosynthesis
Biosynthesis
Cell growth
Cyanobacteria
Enzymes
green algae
Kinases
Metabolism
N-Acetyl-L-glutamate kinase
Nitrates
Nitrogen
PII- signal transduction protein
Polyamines
Proteins
Signal transduction
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Summary:N-Acetyl-L-glutamate kinase (NAGK) catalyzes the rate-limiting step in the ornithine/arginine biosynthesis pathway in eukaryotic and bacterial oxygenic phototrophs. NAGK is the most highly conserved target of the PII signal transduction protein in Cyanobacteria and Archaeplastida (red algae and Chlorophyta). However, there is still much to be learned about how NAGK is regulated in vivo. The use of unicellular green alga Chlamydomonas reinhardtii as a model system has already been instrumental in identifying several key regulation mechanisms that control nitrogen (N) metabolism. With a combination of molecular-genetic and biochemical approaches, we show the existence of the complex CrNAGK control at the transcriptional level, which is dependent on N source and N availability. In growing cells, CrNAGK requires CrPII to properly sense the feedback inhibitor arginine. Moreover, we provide primary evidence that CrPII is only partly responsible for regulating CrNAGK activity to adapt to changing nutritional conditions. Collectively, our results suggest that in vivo CrNAGK is tuned at the transcriptional and post-translational levels, and CrPII and additional as yet unknown factor(s) are integral parts of this regulation.
ISSN:1422-0067
1661-6596
1422-0067
DOI:10.3390/ijms241612873