8OOL

Glutamine synthetase from Methanothermococcus thermolithotrophicus with TbXo4 at a resolution of 1.65 A

This is a non-PDB format compatible entry.

Summary for 8OOL

• Entry DOI: 10.2210/pdb8ool/pdb
• Descriptor: Glutamine synthetase from Methanothermococcus thermolithotrophicus, TERBIUM(III) ION, SULFATE ION, ... (5 entities in total)
• Functional Keywords: nitrogen-assimilation, methanogenic archaea, allosteric activation, hydrogenotrophic, thermophile, marine, crystallophore, glutamate, atp, ligase
• Biological source: Methanothermococcus thermolithotrophicus DSM 2095
• Total number of polymer chains: 6
• Total formula weight: 309596.33

Authors

Mueller, M.-C.,Wagner, T. (deposition date: 2023-04-05, release date: 2024-01-24, Last modification date: 2024-01-31)

Primary citation

Muller, M.C.,Lemaire, O.N.,Kurth, J.M.,Welte, C.U.,Wagner, T.
Differences in regulation mechanisms of glutamine synthetases from methanogenic archaea unveiled by structural investigations.
Commun Biol, 7:111-111, 2024

PubMed Abstract: Glutamine synthetases (GS) catalyze the ATP-dependent ammonium assimilation, the initial step of nitrogen acquisition that must be under tight control to fit cellular needs. While their catalytic mechanisms and regulations are well-characterized in bacteria and eukaryotes, only limited knowledge exists in archaea. Here, we solved two archaeal GS structures and unveiled unexpected differences in their regulatory mechanisms. GS from Methanothermococcus thermolithotrophicus is inactive in its resting state and switched on by 2-oxoglutarate, a sensor of cellular nitrogen deficiency. The enzyme activation overlays remarkably well with the reported cellular concentration for 2-oxoglutarate. Its binding to an allosteric pocket reconfigures the active site through long-range conformational changes. The homolog from Methermicoccus shengliensis does not harbor the 2-oxoglutarate binding motif and, consequently, is 2-oxoglutarate insensitive. Instead, it is directly feedback-inhibited through glutamine recognition by the catalytic Asp50'-loop, a mechanism common to bacterial homologs, but absent in M. thermolithotrophicus due to residue substitution. Analyses of residue conservation in archaeal GS suggest that both regulations are widespread and not mutually exclusive. While the effectors and their binding sites are surprisingly different, the molecular mechanisms underlying their mode of action on GS activity operate on the same molecular determinants in the active site.

PubMed: 38243071
DOI: 10.1038/s42003-023-05726-w

Experimental method

X-RAY DIFFRACTION (1.65 Å)