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Biol 430

Biology Major

Partners: Delo Sarr, Mustafa Husain

spinqualitylabelsall models Glutamine synthetase Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image

Contents 1 Jmol practice 2 Stoichiometry 3 Active Site 4 Reference

Jmol practice

Backbone with ligand

Labeled Ligands in Chain A

Active Site with Amino Acid Residues

Connection between Chain F residue 63 and Chain G residue 319

Stoichiometry

Quarternary Structure

The enzyme Glutamine Synthetase is made up of twelve subunits. The structure consists of two identical hexameric rings held together by hydrophobic and hydrogen bonding forces. The N-terminal helix of each subunit is exposed to hydrophilic solvent, where as the C-terminal is enshrouded in hydrophobic regions within the helical structure of the rings. The central channel is linked together by six four-stranded anti-parallel L-sheets which along with the twelve monomers enhance the stability of the protein structure.

Quarternary Interactions

Interacting subunits are connected through couple of different type of interactions, such as: Hydrogen Bonds, and Non-bonded contacts. Each subunit has area’s that are proportional to the surface area of the corresponding protein chains. Each subunit only interacts with four other protomers in the protein.

Subunit Connections:

A is connected to B with 17 hydrogen bonds and 219 non-bonded contacts

A is connected to F with 16 hydrogen bonds and 215 non-bonded contacts

A is connected to G with 28 hydrogen bonds and 363 non-bonded contacts

A is connected to H with 4 hydrogen bonds and 21 non-bonded contacts

B is connected to C with 17 hydrogen bonds and 217 non-bonded contacts

B is connected to H with 26 hydrogen bonds and 338 non-bonded contacts

B is connected to I with 4 hydrogen bonds and 27 non-bonded contacts

C is connected to D with 19 hydrogen bonds and 230 non-bonded contacts

C is connected to I with 26 hydrogen bonds and 341 non-bonded contacts

C is connected to J with 4 hydrogen bonds and 23 non bonded contacts

D is connected to E with 17 hydrogen bonds and 209 non-bonded contacts

D is connected to J with 26 hydrogen bonds and 343 non-bonded contacts

D is connected to K with 4 hydrogen bonds and 22 non-bonded contacts

E is connected to F with 16 hydrogen bonds and 198 non-bonded contacts

E is connected to K with 28 hydrogen bonds and 353 non-bonded contacts

E is connected to L with 4 hydrogen bonds and 26 non-bonded contacts

G is connected to L with 17 hydrogen bonds and 223 non-bonded contacts

G is connected to H with 18 hydrogen bonds and 212 non-bonded contacts

H is connected to I with 17 hydrogen bonds and 224 non-bonded contacts

I is connected to J with 19 hydrogen bonds and 240 non-bonded contacts

J is connected to K with 18 hydrogen bonds and 224 non-bonded contacts

K is connected to L with 17 hydrogen bonds and 216 non-bonded contacts

Active Site

Since all the subunits are the same, they exhibit several forms of symmetry including and a . Each subunit has an . The active site of glutamine synthetase lies primarily around three manganese atoms. It is surrounded by three important ligands: Phosphinothricin, ADP, TL as labeled in the applet. ADP is short for Adenosite Diphosphate. And the metal ion, Thallium is also labeled in the applet.

Reference

1. Eisenberg, David and Gill, Harindarpal and Pfluegl, Gaston and Rotstein, Sergio. “Structure-function relationships of glutamine synthetases.” Elsevier, archives of biochemistry and biophysics 1477(Dec 1999):122-123.

2. Eisenberg, Gill. "Crystal structure of glutamine synthetase from salmonella typhimurium with thallium ions" PDBsum. european bioinformatics institute 2006-2008. <http://www.ebi.ac.uk/thornton-srv/databases/cgi-bin/pdbsum/GetPage.pl?pdbcode=1f1h&template=main.html>