Glutamine synthetase
From Proteopedia
(Difference between revisions)
| Line 7: | Line 7: | ||
An unrefined structure of glutamine synthetase is made of two layers, each containing 6 subunits, for a total of 12 subunits. <ref name="Yamashita">PMID:2572586 </ref> Each subunit contains an <scene name='Sandbox_169/Mn_in_the_active_site/2'>active site </scene>which is defined by a cylindrical shape formed by six antiparalel β starnds contributed by one subunit and two more strands by the neighbouring subunit.<ref name="Yamashita"/> In each cylindrical active site there are two Mn2+ ions: Mn 2+ 469 and 470. Both are attached to three protein chains and two water molecules, one of the water molecules are shared by both Mn2+. The protein ligands. Attached to Mn 2+ 469 is: Glu-131, GLu-212 and Glu-220, and the protein ligands attached to Mn 2+ are: Glu-129, His-269 and Glu-357.<ref name="Yamashita"/> | An unrefined structure of glutamine synthetase is made of two layers, each containing 6 subunits, for a total of 12 subunits. <ref name="Yamashita">PMID:2572586 </ref> Each subunit contains an <scene name='Sandbox_169/Mn_in_the_active_site/2'>active site </scene>which is defined by a cylindrical shape formed by six antiparalel β starnds contributed by one subunit and two more strands by the neighbouring subunit.<ref name="Yamashita"/> In each cylindrical active site there are two Mn2+ ions: Mn 2+ 469 and 470. Both are attached to three protein chains and two water molecules, one of the water molecules are shared by both Mn2+. The protein ligands. Attached to Mn 2+ 469 is: Glu-131, GLu-212 and Glu-220, and the protein ligands attached to Mn 2+ are: Glu-129, His-269 and Glu-357.<ref name="Yamashita"/> | ||
| - | Unique to glutamine synthetase, unlike other enzymes, is it's "passive site". This refers to the central loop which is formed by a segment of the backbone that extends into the central aqueous cavity.(Ref1)Unlike other sites in glutamine synthetase under the same conditions, this site is suceptible to proteolysis by four secreated proteases from the V8 protease of ''Staphylococcus aureus''.<ref name="Yamashita"/> | + | Unique to glutamine synthetase, unlike other enzymes, is it's "passive site". This refers to the central loop which is formed by a segment of the backbone that extends into the central aqueous cavity.(Ref1)Unlike other sites in glutamine synthetase under the same conditions, this site is suceptible to proteolysis by four secreated proteases from the V8 protease of ''Staphylococcus aureus''.<ref name="Yamashita"/>[[Image:Passive site.png|thumb|Figure 1: A clear view of glutamine synthetases "passive site".]] |
| - | + | ||
| - | [[Image:Passive site.png|thumb|Figure 1: A clear view of glutamine synthetases "passive site".]] | + | |
{{STRUCTURE_2gls| PDB=2gls | SCENE=Sandbox_169/2gls/1 }} | {{STRUCTURE_2gls| PDB=2gls | SCENE=Sandbox_169/2gls/1 }} | ||
| Line 16: | Line 14: | ||
Glutamine synthetase has been described as having three destinctive types:<ref>PMID:7916055 </ref> | Glutamine synthetase has been described as having three destinctive types:<ref>PMID:7916055 </ref> | ||
| - | *Class I (GSI): Genes for this class have only been found in bacteria (eubacteria) and archaea (arhaebacteria | + | *Class I (GSI): Genes for this class have only been found in bacteria (eubacteria) and archaea (arhaebacteria. The paper by Kumada "et. al" goes into detail on these two..<ref name="Kumada">PMID:8096645 </ref> |
*Class II (GSII): Genes for this class have only been found in eukaryotes anda few soil-dwelling bacteria. | *Class II (GSII): Genes for this class have only been found in eukaryotes anda few soil-dwelling bacteria. | ||
*Class III (GSIII): Genes from this class have only been found in a few bacterial species.It is a hexamer of identical chains. It is much larger (about 700 amino acids) than the GSI (450 to 470 amino acids) or GSII (350 to 420 amino acids) enzymes. | *Class III (GSIII): Genes from this class have only been found in a few bacterial species.It is a hexamer of identical chains. It is much larger (about 700 amino acids) than the GSI (450 to 470 amino acids) or GSII (350 to 420 amino acids) enzymes. | ||
| Line 22: | Line 20: | ||
==Function== | ==Function== | ||
| - | Glutamine synthetase (GS) is an essential enzyme in the cellular nitrogen metabolism and has been found to play a role in both ammonia assimilation and glutamine byosynthesis.<ref name="Kumada" | + | Glutamine synthetase (GS) is an essential enzyme in the cellular nitrogen metabolism and has been found to play a role in both ammonia assimilation and glutamine byosynthesis.<ref name="Kumada"/> is the only enzyme capable of glutamine synthesis. The glutamine produced is an essential precursor for purine and pyrimidine synthesis, a modulator of protein turnover or an intermediate for gluconeogenesis and acid-base balance. <ref>He,Youji, Hakvoort,Theodorus, B.M., Kohler,S.Eleonor, Vermeulen,Jacqueline L.M.,Rudi de Waart, D., Theije,Chiel de, Gabrie A.M. ten Have, Van Eijk,Hans M.H., Kunne,Cindy, Labruyere,Wilelmina T., Houten,Sander M., Sokolovic,Mika, Tuijter,Jan M., Deutz,Nicolaas E.P., and Lamers, Wouter H. Glutamine Synthetase in muscle is required for glutamine production druing fasting and extrahepatic ammonia detoxification. The American Society for Biochemistry and Molecular Biology, January 11, 2010 </ref> |
[[Image:Glutamine-synthesis.jpg|thumb|Figure 2: Two step process of sythesis of glutamine from glutamate, synthesised by glutamine synthesis.]] | [[Image:Glutamine-synthesis.jpg|thumb|Figure 2: Two step process of sythesis of glutamine from glutamate, synthesised by glutamine synthesis.]] | ||
Revision as of 22:15, 31 March 2010
Contents |
Glutamine Synthetase
Structure
An unrefined structure of glutamine synthetase is made of two layers, each containing 6 subunits, for a total of 12 subunits. [1] Each subunit contains an which is defined by a cylindrical shape formed by six antiparalel β starnds contributed by one subunit and two more strands by the neighbouring subunit.[1] In each cylindrical active site there are two Mn2+ ions: Mn 2+ 469 and 470. Both are attached to three protein chains and two water molecules, one of the water molecules are shared by both Mn2+. The protein ligands. Attached to Mn 2+ 469 is: Glu-131, GLu-212 and Glu-220, and the protein ligands attached to Mn 2+ are: Glu-129, His-269 and Glu-357.[1]
Unique to glutamine synthetase, unlike other enzymes, is it's "passive site". This refers to the central loop which is formed by a segment of the backbone that extends into the central aqueous cavity.(Ref1)Unlike other sites in glutamine synthetase under the same conditions, this site is suceptible to proteolysis by four secreated proteases from the V8 protease of Staphylococcus aureus.[1]
Classes
Glutamine synthetase has been described as having three destinctive types:[2]
- Class I (GSI): Genes for this class have only been found in bacteria (eubacteria) and archaea (arhaebacteria. The paper by Kumada "et. al" goes into detail on these two..[3]
- Class II (GSII): Genes for this class have only been found in eukaryotes anda few soil-dwelling bacteria.
- Class III (GSIII): Genes from this class have only been found in a few bacterial species.It is a hexamer of identical chains. It is much larger (about 700 amino acids) than the GSI (450 to 470 amino acids) or GSII (350 to 420 amino acids) enzymes.
Function
Glutamine synthetase (GS) is an essential enzyme in the cellular nitrogen metabolism and has been found to play a role in both ammonia assimilation and glutamine byosynthesis.[3] is the only enzyme capable of glutamine synthesis. The glutamine produced is an essential precursor for purine and pyrimidine synthesis, a modulator of protein turnover or an intermediate for gluconeogenesis and acid-base balance. [4]
Image:Glutamine-synthesis.jpg
Figure 2: Two step process of sythesis of glutamine from glutamate, synthesised by glutamine synthesis.
References
- ↑ 1.0 1.1 1.2 1.3 Yamashita MM, Almassy RJ, Janson CA, Cascio D, Eisenberg D. Refined atomic model of glutamine synthetase at 3.5 A resolution. J Biol Chem. 1989 Oct 25;264(30):17681-90. PMID:2572586
- ↑ Brown JR, Masuchi Y, Robb FT, Doolittle WF. Evolutionary relationships of bacterial and archaeal glutamine synthetase genes. J Mol Evol. 1994 Jun;38(6):566-76. PMID:7916055
- ↑ 3.0 3.1 Kumada Y, Benson DR, Hillemann D, Hosted TJ, Rochefort DA, Thompson CJ, Wohlleben W, Tateno Y. Evolution of the glutamine synthetase gene, one of the oldest existing and functioning genes. Proc Natl Acad Sci U S A. 1993 Apr 1;90(7):3009-13. PMID:8096645
- ↑ He,Youji, Hakvoort,Theodorus, B.M., Kohler,S.Eleonor, Vermeulen,Jacqueline L.M.,Rudi de Waart, D., Theije,Chiel de, Gabrie A.M. ten Have, Van Eijk,Hans M.H., Kunne,Cindy, Labruyere,Wilelmina T., Houten,Sander M., Sokolovic,Mika, Tuijter,Jan M., Deutz,Nicolaas E.P., and Lamers, Wouter H. Glutamine Synthetase in muscle is required for glutamine production druing fasting and extrahepatic ammonia detoxification. The American Society for Biochemistry and Molecular Biology, January 11, 2010
| Please do NOT make changes to this Sandbox until after April 23, 2010. Sandboxes 151-200 are reserved until then for use by the Chemistry 307 class at UNBC taught by Prof. Andrea Gorrell. |
Proteopedia Page Contributors and Editors (what is this?)
Michal Harel, Rhiannon Khela, David Canner, Andrea Gorrell, Alexander Berchansky, Jaime Prilusky
