4s0r

Structural highlights

Function

GLN1A_BACSU Glutamine synthetase (GS) is an unusual multitasking protein that functions as an enzyme, a transcription coregulator, and a chaperone in ammonium assimilation and in the regulation of genes involved in nitrogen metabolism (PubMed:25691471). It catalyzes the ATP-dependent biosynthesis of glutamine from glutamate and ammonia (PubMed:24158439). Feedback-inhibited GlnA interacts with and regulates the activity of the transcriptional regulator TnrA (PubMed:11719184, PubMed:12139611). During nitrogen limitation, TnrA is in its DNA-binding active state and turns on the transcription of genes required for nitrogen assimilation (PubMed:11719184, PubMed:12139611, PubMed:25691471). Under conditions of nitrogen excess, feedback-inhibited GlnA forms a stable complex with TnrA, which inhibits its DNA-binding activity (PubMed:11719184, PubMed:12139611, PubMed:25691471). In contrast, feedback-inhibited GlnA acts as a chaperone to stabilize the DNA-binding activity of GlnR, which represses the transcription of nitrogen assimilation genes (PubMed:25691471).^{[1] [2] [3] [4]}

See Also

• Glutamine synthetase 3D structures

References

1. ↑ Wray LV Jr, Zalieckas JM, Fisher SH. Bacillus subtilis glutamine synthetase controls gene expression through a protein-protein interaction with transcription factor TnrA. Cell. 2001 Nov 16;107(4):427-35. PMID:11719184
2. ↑ Fisher SH, Brandenburg JL, Wray LV Jr. Mutations in Bacillus subtilis glutamine synthetase that block its interaction with transcription factor TnrA. Mol Microbiol. 2002 Aug;45(3):627-35. doi: 10.1046/j.1365-2958.2002.03054.x. PMID:12139611 doi:http://dx.doi.org/10.1046/j.1365-2958.2002.03054.x
3. ↑ Murray DS, Chinnam N, Tonthat NK, Whitfill T, Wray LV, Fisher SH, Schumacher MA. Structures of the B. subtilis glutamine synthetase dodecamer reveal large intersubunit catalytic conformational changes linked to a unique feedback inhibition mechanism. J Biol Chem. 2013 Oct 24. PMID:24158439 doi:http://dx.doi.org/10.1074/jbc.M113.519496
4. ↑ Schumacher MA, Chinnam NB, Cuthbert B, Tonthat NK, Whitfill T. Structures of regulatory machinery reveal novel molecular mechanisms controlling B. subtilis nitrogen homeostasis. Genes Dev. 2015 Feb 15;29(4):451-64. doi: 10.1101/gad.254714.114. PMID:25691471 doi:http://dx.doi.org/10.1101/gad.254714.114