TY - JOUR

T1 - Micromonas commoda N-Acetyl-L-Glutamate Kinase Reflects Specificity in the Control of Arginine Synthesis at the Base of the Green Line

AU - Власова, Виталина Анатольевна

AU - Лапина, Татьяна Викторовна

AU - Ермилова, Елена Викторовна

PY - 2026/2/18

Y1 - 2026/2/18

N2 - N-Acetyl-L-glutamate kinase (NAGK) catalyzes the first committed step in arginine biosynthesis in organisms that perform the cyclic pathway of ornithine synthesis. In cyanobacteria and most Archaeplastida, the activity of NAGK is controlled by the PII signal transduction protein. During evolution, representatives of the class Mamiellophyceae, Ostreococcus and Bathycoccus lost the gene encoding PII, while Micromonas retained this gene. Here, we perform coupled enzyme and pull-down assays and show that M. commoda NAGK is activated by N-acetyl-L-glutamate and inhibited by arginine but is not controlled by PII proteins. This loss may have been compensated for by the enzyme's low sensitivity to arginine. In contrast, M. commoda PII relieved Chlamydomonas reinhardtii NAGK from feedback inhibition by arginine. These observations suggest that M. commoda NAGK possesses a unique feature: it has lost the ability to interact with PII protein. The findings are discussed in the context of the relationship between NAGK control and the PII role in Mamiellophyceae.

AB - N-Acetyl-L-glutamate kinase (NAGK) catalyzes the first committed step in arginine biosynthesis in organisms that perform the cyclic pathway of ornithine synthesis. In cyanobacteria and most Archaeplastida, the activity of NAGK is controlled by the PII signal transduction protein. During evolution, representatives of the class Mamiellophyceae, Ostreococcus and Bathycoccus lost the gene encoding PII, while Micromonas retained this gene. Here, we perform coupled enzyme and pull-down assays and show that M. commoda NAGK is activated by N-acetyl-L-glutamate and inhibited by arginine but is not controlled by PII proteins. This loss may have been compensated for by the enzyme's low sensitivity to arginine. In contrast, M. commoda PII relieved Chlamydomonas reinhardtii NAGK from feedback inhibition by arginine. These observations suggest that M. commoda NAGK possesses a unique feature: it has lost the ability to interact with PII protein. The findings are discussed in the context of the relationship between NAGK control and the PII role in Mamiellophyceae.

KW - Mamiellophyceae

KW - PII proteins

KW - amino acid metabolism

UR - https://www.mendeley.com/catalogue/d20114d8-9bdc-33f4-83ef-4968a134f489/

U2 - 10.3390/ijms27041939

DO - 10.3390/ijms27041939

M3 - Article

C2 - 41752075

VL - 27

JO - International Journal of Molecular Sciences

JF - International Journal of Molecular Sciences

SN - 1422-0067

IS - 4

M1 - 1939

ER -