1m6v
From Proteopedia
(New page: 200px<br /><applet load="1m6v" size="450" color="white" frame="true" align="right" spinBox="true" caption="1m6v, resolution 2.10Å" /> '''Crystal Structure of...) |
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| - | [[Image:1m6v.jpg|left|200px]]<br /><applet load="1m6v" size=" | + | [[Image:1m6v.jpg|left|200px]]<br /><applet load="1m6v" size="350" color="white" frame="true" align="right" spinBox="true" |
caption="1m6v, resolution 2.10Å" /> | caption="1m6v, resolution 2.10Å" /> | ||
'''Crystal Structure of the G359F (small subunit) Point Mutant of Carbamoyl Phosphate Synthetase'''<br /> | '''Crystal Structure of the G359F (small subunit) Point Mutant of Carbamoyl Phosphate Synthetase'''<br /> | ||
==Overview== | ==Overview== | ||
| - | Carbamoyl-phosphate synthetase catalyzes the production of carbamoyl | + | Carbamoyl-phosphate synthetase catalyzes the production of carbamoyl phosphate through a reaction mechanism requiring one molecule of bicarbonate, two molecules of MgATP, and one molecule of glutamine. The enzyme from Escherichia coli is composed of two polypeptide chains. The smaller of these belongs to the Class I amidotransferase superfamily and contains all of the necessary amino acid side chains required for the hydrolysis of glutamine to glutamate and ammonia. Two homologous domains from the larger subunit adopt conformations that are characteristic for members of the ATP-grasp superfamily. Each of these ATP-grasp domains contains an active site responsible for binding one molecule of MgATP. High resolution x-ray crystallographic analyses have shown that, remarkably, the three active sites in the E. coli enzyme are connected by a molecular tunnel of approximately 100 A in total length. Here we describe the high resolution x-ray crystallographic structure of the G359F (small subunit) mutant protein of carbamoyl phosphate synthetase. This residue was initially targeted for study because it resides within the interior wall of the molecular tunnel leading from the active site of the small subunit to the first active site of the large subunit. It was anticipated that a mutation to the larger residue would "clog" the ammonia tunnel and impede the delivery of ammonia from its site of production to the site of utilization. In fact, the G359F substitution resulted in a complete change in the conformation of the loop delineated by Glu-355 to Ala-364, thereby providing an "escape" route for the ammonia intermediate directly to the bulk solvent. The substitution also effected the disposition of several key catalytic amino acid side chains in the small subunit active site. |
==About this Structure== | ==About this Structure== | ||
| - | 1M6V is a [http://en.wikipedia.org/wiki/Protein_complex Protein complex] structure of sequences from [http://en.wikipedia.org/wiki/Escherichia_coli Escherichia coli] with MN, K, CL, PO4, ADP, ORN and NET as [http://en.wikipedia.org/wiki/ligands ligands]. Active as [http://en.wikipedia.org/wiki/Carbamoyl-phosphate_synthase_(glutamine-hydrolyzing) Carbamoyl-phosphate synthase (glutamine-hydrolyzing)], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=6.3.5.5 6.3.5.5] Full crystallographic information is available from [http:// | + | 1M6V is a [http://en.wikipedia.org/wiki/Protein_complex Protein complex] structure of sequences from [http://en.wikipedia.org/wiki/Escherichia_coli Escherichia coli] with <scene name='pdbligand=MN:'>MN</scene>, <scene name='pdbligand=K:'>K</scene>, <scene name='pdbligand=CL:'>CL</scene>, <scene name='pdbligand=PO4:'>PO4</scene>, <scene name='pdbligand=ADP:'>ADP</scene>, <scene name='pdbligand=ORN:'>ORN</scene> and <scene name='pdbligand=NET:'>NET</scene> as [http://en.wikipedia.org/wiki/ligands ligands]. Active as [http://en.wikipedia.org/wiki/Carbamoyl-phosphate_synthase_(glutamine-hydrolyzing) Carbamoyl-phosphate synthase (glutamine-hydrolyzing)], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=6.3.5.5 6.3.5.5] Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1M6V OCA]. |
==Reference== | ==Reference== | ||
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[[Category: Escherichia coli]] | [[Category: Escherichia coli]] | ||
[[Category: Protein complex]] | [[Category: Protein complex]] | ||
| - | [[Category: Holden, H | + | [[Category: Holden, H M.]] |
[[Category: Huang, X.]] | [[Category: Huang, X.]] | ||
| - | [[Category: Raushel, F | + | [[Category: Raushel, F M.]] |
| - | [[Category: Thoden, J | + | [[Category: Thoden, J B.]] |
[[Category: ADP]] | [[Category: ADP]] | ||
[[Category: CL]] | [[Category: CL]] | ||
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[[Category: tunnel]] | [[Category: tunnel]] | ||
| - | ''Page seeded by [http:// | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 13:52:13 2008'' |
Revision as of 11:52, 21 February 2008
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Crystal Structure of the G359F (small subunit) Point Mutant of Carbamoyl Phosphate Synthetase
Overview
Carbamoyl-phosphate synthetase catalyzes the production of carbamoyl phosphate through a reaction mechanism requiring one molecule of bicarbonate, two molecules of MgATP, and one molecule of glutamine. The enzyme from Escherichia coli is composed of two polypeptide chains. The smaller of these belongs to the Class I amidotransferase superfamily and contains all of the necessary amino acid side chains required for the hydrolysis of glutamine to glutamate and ammonia. Two homologous domains from the larger subunit adopt conformations that are characteristic for members of the ATP-grasp superfamily. Each of these ATP-grasp domains contains an active site responsible for binding one molecule of MgATP. High resolution x-ray crystallographic analyses have shown that, remarkably, the three active sites in the E. coli enzyme are connected by a molecular tunnel of approximately 100 A in total length. Here we describe the high resolution x-ray crystallographic structure of the G359F (small subunit) mutant protein of carbamoyl phosphate synthetase. This residue was initially targeted for study because it resides within the interior wall of the molecular tunnel leading from the active site of the small subunit to the first active site of the large subunit. It was anticipated that a mutation to the larger residue would "clog" the ammonia tunnel and impede the delivery of ammonia from its site of production to the site of utilization. In fact, the G359F substitution resulted in a complete change in the conformation of the loop delineated by Glu-355 to Ala-364, thereby providing an "escape" route for the ammonia intermediate directly to the bulk solvent. The substitution also effected the disposition of several key catalytic amino acid side chains in the small subunit active site.
About this Structure
1M6V is a Protein complex structure of sequences from Escherichia coli with , , , , , and as ligands. Active as Carbamoyl-phosphate synthase (glutamine-hydrolyzing), with EC number 6.3.5.5 Full crystallographic information is available from OCA.
Reference
Carbamoyl-phosphate synthetase. Creation of an escape route for ammonia., Thoden JB, Huang X, Raushel FM, Holden HM, J Biol Chem. 2002 Oct 18;277(42):39722-7. Epub 2002 Jul 18. PMID:12130656
Page seeded by OCA on Thu Feb 21 13:52:13 2008
Categories: Carbamoyl-phosphate synthase (glutamine-hydrolyzing) | Escherichia coli | Protein complex | Holden, H M. | Huang, X. | Raushel, F M. | Thoden, J B. | ADP | CL | K | MN | NET | ORN | PO4 | Substrate channeling | Tunnel
