Glutamine synthetase
From Proteopedia
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Rhiannon Khela
Structure
An unrefined structure of glutamine synthetase is made of two layers, each containing 6 subunits, for a total of 12 subunits. [1] Each active site is defined by a cylindrical shape formed by six antiparalel β starnds contributed by one subunit and two strands by the neighbouring subunit.[2] In each cylindrical active site there are two Mn2+ ions, both of which are have three protein chains and two water molecules, one water shared by both Mn2+. For the protein ligands to Mn 2+ 469, Glu-131, GLu-212 and Glu-220 are attached and for the Mn2+, Glu-129, His-269 and Glu-357 are designated.
Classes
Glutamine synthetase has been described as having three destinctive types:[3] Class I (GSI): Genes for this class have only been found in bacteria (eubacteria) and archaea (arhaebacteria) 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.
Function
Glutamine synthetase is an essential enzyme in the cellular nitrogen metabolism and has been found to play a role in both ammonia assimilation and glutamine byosynthesis.[4] Image:Glutamine-synthesis.jpg
References
- ↑ 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
- ↑ 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
- ↑ 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
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Michal Harel, Rhiannon Khela, David Canner, Andrea Gorrell, Alexander Berchansky, Jaime Prilusky