1hto
From Proteopedia
(New page: 200px<br /><applet load="1hto" size="450" color="white" frame="true" align="right" spinBox="true" caption="1hto, resolution 2.40Å" /> '''CRYSTALLOGRAPHIC STR...) |
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| - | [[Image:1hto.gif|left|200px]]<br /><applet load="1hto" size=" | + | [[Image:1hto.gif|left|200px]]<br /><applet load="1hto" size="350" color="white" frame="true" align="right" spinBox="true" |
caption="1hto, resolution 2.40Å" /> | caption="1hto, resolution 2.40Å" /> | ||
'''CRYSTALLOGRAPHIC STRUCTURE OF A RELAXED GLUTAMINE SYNTHETASE FROM MYCOBACTERIUM TUBERCULOSIS'''<br /> | '''CRYSTALLOGRAPHIC STRUCTURE OF A RELAXED GLUTAMINE SYNTHETASE FROM MYCOBACTERIUM TUBERCULOSIS'''<br /> | ||
==Overview== | ==Overview== | ||
| - | The crystal structure of glutamine synthetase (GS) from Mycobacterium | + | The crystal structure of glutamine synthetase (GS) from Mycobacterium tuberculosis determined at 2.4 A resolution reveals citrate and AMP bound in the active site. The structure was refined with strict 24-fold noncrystallographic symmetry (NCS) constraints and has an R-factor of 22.7% and an R-free of 25.5%. Multicopy refinement using 10 atomic models and strict 24-fold NCS constraints further reduced the R-factor to 20.4% and the R-free to 23.2%. The multicopy model demonstrates the range of atomic displacements of catalytic and regulatory loops in glutamine synthesis, simulating loop motions. A comparison with loop positions in substrate complexes of GS from Salmonella typhimurium shows that the Asp50 and Glu327 loops close over the active site during catalysis. These loop closures are preceded by a conformational change of the Glu209 beta-strand upon metal ion or ATP binding that converts the enzyme from a relaxed to a taut state. We propose a model of the GS regulatory mechanism based on the loop motions in which adenylylation of the Tyr397 loop reverses the effect of metal ion binding, and regulates intermediate formation by preventing closure of the Glu327 loop. |
==About this Structure== | ==About this Structure== | ||
| - | 1HTO is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Mycobacterium_tuberculosis Mycobacterium tuberculosis] with MN, AMP and CIT as [http://en.wikipedia.org/wiki/ligands ligands]. Active as [http://en.wikipedia.org/wiki/Glutamate--ammonia_ligase Glutamate--ammonia ligase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=6.3.1.2 6.3.1.2] Full crystallographic information is available from [http:// | + | 1HTO is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Mycobacterium_tuberculosis Mycobacterium tuberculosis] with <scene name='pdbligand=MN:'>MN</scene>, <scene name='pdbligand=AMP:'>AMP</scene> and <scene name='pdbligand=CIT:'>CIT</scene> as [http://en.wikipedia.org/wiki/ligands ligands]. Active as [http://en.wikipedia.org/wiki/Glutamate--ammonia_ligase Glutamate--ammonia ligase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=6.3.1.2 6.3.1.2] Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1HTO OCA]. |
==Reference== | ==Reference== | ||
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[[Category: Single protein]] | [[Category: Single protein]] | ||
[[Category: Eisenberg, D.]] | [[Category: Eisenberg, D.]] | ||
| - | [[Category: Gill, H | + | [[Category: Gill, H S.]] |
| - | [[Category: TBSGC, TB | + | [[Category: TBSGC, TB Structural Genomics Consortium.]] |
[[Category: AMP]] | [[Category: AMP]] | ||
[[Category: CIT]] | [[Category: CIT]] | ||
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[[Category: tbsgc]] | [[Category: tbsgc]] | ||
| - | ''Page seeded by [http:// | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 13:04:53 2008'' |
Revision as of 11:04, 21 February 2008
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CRYSTALLOGRAPHIC STRUCTURE OF A RELAXED GLUTAMINE SYNTHETASE FROM MYCOBACTERIUM TUBERCULOSIS
Overview
The crystal structure of glutamine synthetase (GS) from Mycobacterium tuberculosis determined at 2.4 A resolution reveals citrate and AMP bound in the active site. The structure was refined with strict 24-fold noncrystallographic symmetry (NCS) constraints and has an R-factor of 22.7% and an R-free of 25.5%. Multicopy refinement using 10 atomic models and strict 24-fold NCS constraints further reduced the R-factor to 20.4% and the R-free to 23.2%. The multicopy model demonstrates the range of atomic displacements of catalytic and regulatory loops in glutamine synthesis, simulating loop motions. A comparison with loop positions in substrate complexes of GS from Salmonella typhimurium shows that the Asp50 and Glu327 loops close over the active site during catalysis. These loop closures are preceded by a conformational change of the Glu209 beta-strand upon metal ion or ATP binding that converts the enzyme from a relaxed to a taut state. We propose a model of the GS regulatory mechanism based on the loop motions in which adenylylation of the Tyr397 loop reverses the effect of metal ion binding, and regulates intermediate formation by preventing closure of the Glu327 loop.
About this Structure
1HTO is a Single protein structure of sequence from Mycobacterium tuberculosis with , and as ligands. Active as Glutamate--ammonia ligase, with EC number 6.3.1.2 Full crystallographic information is available from OCA.
Reference
Multicopy crystallographic refinement of a relaxed glutamine synthetase from Mycobacterium tuberculosis highlights flexible loops in the enzymatic mechanism and its regulation., Gill HS, Pfluegl GM, Eisenberg D, Biochemistry. 2002 Aug 6;41(31):9863-72. PMID:12146952
Page seeded by OCA on Thu Feb 21 13:04:53 2008
Categories: Glutamate--ammonia ligase | Mycobacterium tuberculosis | Single protein | Eisenberg, D. | Gill, H S. | TBSGC, TB Structural Genomics Consortium. | AMP | CIT | MN | Citrate | Glutamine synthetase | Protein structure initiative | Psi | Structural genomics | Tb structural genomics consortium | Tbsgc
