TY - JOUR

T1 - N-Acetyl-L-glutamate Kinase of Chlamydomonas reinhardtii: In Vivo Regulation by PII Protein and Beyond

AU - Власова, Виталина Анатольевна

AU - Лапина, Татьяна Викторовна

AU - Статинов, Владислав Романович

AU - Ермилова, Елена Викторовна

PY - 2023/8/17

Y1 - 2023/8/17

N2 - 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.

AB - 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.

KW - Arginine

KW - Biotin

KW - Chlamydomonas reinhardtii/genetics

KW - Eukaryota

KW - green algae

KW - PII- signal transduction protein

KW - arginine biosynthesis

KW - N-Acetyl-L-glutamate kinase

UR - https://www.mendeley.com/catalogue/1ef87538-c32d-3257-b2b6-832d08f6b7fa/

U2 - 10.3390/ijms241612873

DO - 10.3390/ijms241612873

M3 - Article

C2 - 37629055

VL - 24

JO - International Journal of Molecular Sciences

JF - International Journal of Molecular Sciences

SN - 1422-0067

IS - 16

M1 - 12873

ER -