From Proteopedia

spinqualitylabelsall models PDB ID 2gls Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image
2gls, resolution 3.50Å ()
Ligands:
Activity:	Glutamate--ammonia ligase, with EC number 6.3.1.2
Structural annotation: Resources: CATH : 2Glsa02, 2Glsa01, 2Glsb02, 2Glsb01, 2Glsc01, 2Glsc02, 2Glsd02, 2Glsd01, 2Glse02, 2Glse01, 2Glsf02, 2Glsf01, 2Glsg01, 2Glsg02, 2Glsh02, 2Glsh01, 2Glsi02, 2Glsi01, 2Glsj01, 2Glsj02, 2Glsk01, 2Glsk02, 2Glsl02, 2Glsl01 InterPro : Ipr014746, Ipr008146, Ipr001637, Ipr008147, Ipr004809 Pfam : PF00120, PF03951 SCOP : d2glsa2, d2glsa1, d2glsb2, d2glsb1, d2glsc1, d2glsc2, d2glsd2, d2glsd1, d2glse2, d2glse1, d2glsf1, d2glsf2, d2glsg2, d2glsg1, d2glsh2, d2glsh1, d2glsi2, d2glsi1, d2glsj2, d2glsj1, d2glsk1, d2glsk2, d2glsl2, d2glsl1 UniProt : P0A1P6
Functional annotation: Cellular component: cytoplasm Biological process: nitrogen compound metabolic process glutamine biosynthetic process nitrogen fixation Molecular function: ligase activity nucleotide binding glutamate-ammonia ligase activity catalytic activity
Evolutionary conservation: Toggle Conservation Colors: Rows = identical sequences: Further Information: Caveats, Explanation, Complete Results at ConSurfDB
Resources:	FirstGlance, OCA, PDBsum, RCSB
Coordinates:	save as pdb, mmCIF, xml

Glutamine Synthetase: Secondary structures

Glutamine synthetase is composed of 12 . Each subunit is composed of 15 and . Each subunit binds 2 Mn for a total of per Glutamine Synthetase.

The beta strands are arranged into 5 . In addition, there are 5 and 5 . ^[1] β-bulges are distortions in β-sheets resulting from the addition of an extra residue due to mutation. Their presence allows the proteins to conserve their structure by maintaining the hydrogen bond pattern.^[2] At the level of the backbone structure, β-bulges can cause a simple aneurysm of the β-sheet. Furthermore, a beta bulge can cause a β-sheet to fold over and cross itself.
Within each subunit there are 46 beta turns. These beta turns join secondary structures such as β-sheets and alpha helices when they need to abruptly change directions and usually occur at the protein surface.^[3]
Some important Secondary structures:
The These are important for quaternary stability.

Each subunit has an exposed NH2 terminus and buried COOH terminus as part of a , colored in red. The helical thong is used as an anchor inside another subunit. ^[4]

The active site within the secondary structure can be called a "bifunnel," providing access to ATP and glutamate at opposing ends.^[5]

The only ligand present is a pair of Mn ions (Manganese) that indicates the active site of each subunit of the dodecamer.

Glutamine synthetase contains the .

References

1. ↑ European Bioinformatics Institute, Ligase(amide synthetase), http://www.ebi.ac.uk/thornton-srv/databases/cgi-bin/pdbsum/GetPage.pl?pdbcode=2gls, Accessed December 18, 2008.
2. ↑ Donald Voet, Judith G. Voet, Charlotte W. Pratt. Fundamentals of Biochemistry life at the molecular level. New Jersey: Wiley,2006.
3. ↑ Donald Voet, Judith G. Voet, Charlotte W. Pratt. Fundamentals of Biochemistry life at the molecular level. New Jersey: Wiley,2006.
4. ↑ Yamashita, M., et al.,Refined Atomic Model of Glutamine Synthetase at 3.5A Resolution, The Journal of Biological Chemistry, 1989, 17681-17690.
5. ↑ Eisenberg, D., et al., Structure-function relationships of glutamine synthetases, Biochimica et Biophysica Acta 1477 (2000), 122-145.