Glutamine synthetase: Difference between revisions
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'''Glutamine synthetase''' (GS) ({{EC number|6.3.1.2}})<ref> Some evolutionary relationships of the primary biological catalysts glutamine synthetase and RuBisCO. |
'''Glutamine synthetase''' (GS) ({{EC number|6.3.1.2}})<ref name="pmid2900091">{{cite journal | author = Eisenberg D, Almassy RJ, Janson CA, Chapman MS, Suh SW, Cascio D, Smith WW | title = Some evolutionary relationships of the primary biological catalysts glutamine synthetase and RuBisCO | journal = Cold Spring Harb. Symp. Quant. Biol. | volume = 52 | issue = | pages = 483–90 | year = 1987 | pmid = 2900091 | doi = | url = | issn = }}</ref> is an [[enzyme]] that plays an essential role in the [[metabolism]] of [[nitrogen]] by catalyzing the condensation of [[glutamate]] and [[ammonia]] to form [[glutamine]]: |
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Glutamate + [[Adenosine triphosphate|ATP]] + NH<sub>3</sub> → Glutamine + [[Adenosine diphosphate|ADP]] + phosphate + H<sub>2</sub>O |
Glutamate + [[Adenosine triphosphate|ATP]] + NH<sub>3</sub> → Glutamine + [[Adenosine diphosphate|ADP]] + phosphate + H<sub>2</sub>O |
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==GS classes== |
==GS classes== |
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There seem to be three different classes of GS: |
There seem to be three different classes of GS:<ref name="pmid8096645">{{cite journal | author = Kumada Y, Benson DR, Hillemann D, Hosted TJ, Rochefort DA, Thompson CJ, Wohlleben W, Tateno Y | title = Evolution of the glutamine synthetase gene, one of the oldest existing and functioning genes | journal = Proc. Natl. Acad. Sci. U.S.A. | volume = 90 | issue = 7 | pages = 3009–13 | year = 1993 | month = April | pmid = 8096645 | pmc = 46226 | doi = | url = | issn = }}</ref><ref name="pmid2575672">{{cite journal | author = Shatters RG, Kahn ML | title = Glutamine synthetase II in Rhizobium: reexamination of the proposed horizontal transfer of DNA from eukaryotes to prokaryotes | journal = J. Mol. Evol. | volume = 29 | issue = 5 | pages = 422–8 | year = 1989 | month = November | pmid = 2575672 | doi = | url = | issn = }}</ref><ref name="pmid7916055">{{cite journal | author = Brown JR, Masuchi Y, Robb FT, Doolittle WF | title = Evolutionary relationships of bacterial and archaeal glutamine synthetase genes | journal = J. Mol. Evol. | volume = 38 | issue = 6 | pages = 566–76 | year = 1994 | month = June | pmid = 7916055 | doi = | url = | issn = }}</ref> |
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* Class I enzymes (GSI) are specific to [[prokaryotes]], and are oligomers of 12 identical [[subunits]]. |
* Class I enzymes (GSI) are specific to [[prokaryotes]], and are oligomers of 12 identical [[subunits]].<ref name="url160.114.99.91">{{cite web | url = http://160.114.99.91/astrojan/protein/pictures/glnsd.jpg | title = GSI structure | author = | authorlink = | coauthors = | date = | format = | work = | publisher = | pages = | language = | archiveurl = | archivedate = | quote = | accessdate = 2009-03-31}}</ref> The activity of GSI-type enzyme is controlled by the adenylation of a [[tyrosine]] residue. The adenylated enzyme is inactive <ref> [http://www.ebi.ac.uk/interpro/DisplayIproEntry?ac=IPR001637 InterPro:IPR001637 Glutamine synthetase class-I, adenylation site]</ref>. |
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* Class II enzymes (GSII) are found in [[eukaryotes]] and in bacteria belonging to the [[Rhizobiaceae]], [[Frankiaceae]], and [[Streptomycetaceae]] families (these bacteria have also a class-I GS). GSII are [[decamer]] of identical subunits |
* Class II enzymes (GSII) are found in [[eukaryotes]] and in bacteria belonging to the [[Rhizobiaceae]], [[Frankiaceae]], and [[Streptomycetaceae]] families (these bacteria have also a class-I GS). GSII are [[decamer]] of identical subunits.<ref name="pmid18005987">{{PDB|2OJW}}; {{cite journal | author = Krajewski WW, Collins R, Holmberg-Schiavone L, Jones TA, Karlberg T, Mowbray SL | title = Crystal structures of mammalian glutamine synthetases illustrate substrate-induced conformational changes and provide opportunities for drug and herbicide design | journal = J. Mol. Biol. | volume = 375 | issue = 1 | pages = 217–28 | year = 2008 | month = January | pmid = 18005987 | doi = 10.1016/j.jmb.2007.10.029 | url = | issn = }}</ref> |
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Plants have two or more isozymes of GSII, one of the isozymes is translocated into the [[chloroplast]]. |
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* Class III enzymes (GSIII) has, currently, only been found in ''[[Bacteroides fragilis]]'' and in ''[[Butyrivibrio fibrisolvens]]''. 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 enzymes (GSIII) has, currently, only been found in ''[[Bacteroides fragilis]]'' and in ''[[Butyrivibrio fibrisolvens]]''. 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. |
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==Inhibitors== |
==Inhibitors== |
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* [[Phosphinothricin]]<ref name="pmid11329256">{{cite journal | author = Gill HS, Eisenberg D | title = The crystal structure of phosphinothricin in the active site of glutamine synthetase illuminates the mechanism of enzymatic inhibition | journal = Biochemistry | volume = 40 | issue = 7 | pages = 1903–12 | year = 2001 | month = February | pmid = 11329256 | doi = 10.1021/bi002438h | url = | issn = }}</ref> |
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* [[Phosphinothricin]] <ref>http://www.ncbi.nlm.nih.gov/pubmed/11329256 Biochemistry. 2001 Feb 20;40(7):1903-12. |
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The crystal structure of phosphinothricin in the active site of glutamine synthetase illuminates the mechanism of enzymatic inhibition. |
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Gill HS, Eisenberg D. |
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</ref> |
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== References == |
== References == |
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{{Reflist}} |
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<references/> |
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== External links == |
== External links == |
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Revision as of 18:55, 31 March 2009
| Glutamine synthetase | |||||||
|---|---|---|---|---|---|---|---|
| Identifiers | |||||||
| Symbol | GLUL | ||||||
| NCBI gene | 2752 | ||||||
| OMIM | 138290 | ||||||
| RefSeq | NM_002065 | ||||||
| UniProt | P15104 | ||||||
| Other data | |||||||
| EC number | 6.3.1.2 | ||||||
| Locus | Chr. 1 q31 | ||||||
| |||||||
Glutamine synthetase (GS) (EC 6.3.1.2)[1] is an enzyme that plays an essential role in the metabolism of nitrogen by catalyzing the condensation of glutamate and ammonia to form glutamine:
Glutamate + ATP + NH3 → Glutamine + ADP + phosphate + H2O
GS classes
There seem to be three different classes of GS:[2][3][4]
- Class I enzymes (GSI) are specific to prokaryotes, and are oligomers of 12 identical subunits.[5] The activity of GSI-type enzyme is controlled by the adenylation of a tyrosine residue. The adenylated enzyme is inactive [6].
- Class II enzymes (GSII) are found in eukaryotes and in bacteria belonging to the Rhizobiaceae, Frankiaceae, and Streptomycetaceae families (these bacteria have also a class-I GS). GSII are decamer of identical subunits.[7]
Plants have two or more isozymes of GSII, one of the isozymes is translocated into the chloroplast.
- Class III enzymes (GSIII) has, currently, only been found in Bacteroides fragilis and in Butyrivibrio fibrisolvens. 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.
While the three classes of GS's are clearly structurally related, the sequence similarities are not so extensive.
Inhibitors
References
- ^ Eisenberg D, Almassy RJ, Janson CA, Chapman MS, Suh SW, Cascio D, Smith WW (1987). "Some evolutionary relationships of the primary biological catalysts glutamine synthetase and RuBisCO". Cold Spring Harb. Symp. Quant. Biol. 52: 483–90. PMID 2900091.
{{cite journal}}: CS1 maint: multiple names: authors list (link) - ^ Kumada Y, Benson DR, Hillemann D, Hosted TJ, Rochefort DA, Thompson CJ, Wohlleben W, Tateno Y (1993). "Evolution of the glutamine synthetase gene, one of the oldest existing and functioning genes". Proc. Natl. Acad. Sci. U.S.A. 90 (7): 3009–13. PMC 46226. PMID 8096645.
{{cite journal}}: Unknown parameter|month=ignored (help)CS1 maint: multiple names: authors list (link) - ^ Shatters RG, Kahn ML (1989). "Glutamine synthetase II in Rhizobium: reexamination of the proposed horizontal transfer of DNA from eukaryotes to prokaryotes". J. Mol. Evol. 29 (5): 422–8. PMID 2575672.
{{cite journal}}: Unknown parameter|month=ignored (help) - ^ Brown JR, Masuchi Y, Robb FT, Doolittle WF (1994). "Evolutionary relationships of bacterial and archaeal glutamine synthetase genes". J. Mol. Evol. 38 (6): 566–76. PMID 7916055.
{{cite journal}}: Unknown parameter|month=ignored (help)CS1 maint: multiple names: authors list (link) - ^ "GSI structure". Retrieved 2009-03-31.
{{cite web}}: Cite has empty unknown parameter:|coauthors=(help) - ^ InterPro:IPR001637 Glutamine synthetase class-I, adenylation site
- ^ PDB: 2OJW; Krajewski WW, Collins R, Holmberg-Schiavone L, Jones TA, Karlberg T, Mowbray SL (2008). "Crystal structures of mammalian glutamine synthetases illustrate substrate-induced conformational changes and provide opportunities for drug and herbicide design". J. Mol. Biol. 375 (1): 217–28. doi:10.1016/j.jmb.2007.10.029. PMID 18005987.
{{cite journal}}: Unknown parameter|month=ignored (help)CS1 maint: multiple names: authors list (link) - ^ Gill HS, Eisenberg D (2001). "The crystal structure of phosphinothricin in the active site of glutamine synthetase illuminates the mechanism of enzymatic inhibition". Biochemistry. 40 (7): 1903–12. doi:10.1021/bi002438h. PMID 11329256.
{{cite journal}}: Unknown parameter|month=ignored (help)
