2gls
From Proteopedia
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==Overview== | ==Overview== | ||
| - | An atomic model of 43,692 non-hydrogen atoms has been determined for the | + | An atomic model of 43,692 non-hydrogen atoms has been determined for the 12-subunit enzyme glutamine synthetase from Salmonella typhimurium, by methods of x-ray diffraction including restrained least-squares atomic refinement against 65,223 unique reflections. At 3.5 A resolution the crystallographic R-factor (on 2 sigma data) is 25.8%. As reported earlier for the unrefined structure, the 12 subunits are arranged in two layers of six; at the interface of pairs of subunits within each layer, cylindrical active sites are formed by six anti-parallel beta strands contributed by one subunit and two strands by the neighboring subunit. This interpretation of the electron density map has now been supported by comparison with glutamine synthetase from Escherichia coli by the Fourier difference method. Each active site cylinder holds two Mn2+ ions, with each ion having as ligands three protein side chains and two water molecules (one water shared by both metals), as well as a histidyl side chain just beyond liganding distance. The protein ligands to Mn2+ 469 are Glu-131, Glu-212, and Glu-220; those to Mn2+ 470 are Glu-129, His-269, and Glu-357. The two layers of subunits are held together largely by the apolar COOH terminus, a helical thong, which inserts into a hydrophobic pocket formed by two neighboring subunits on the opposite ring. Also between layers, there is a hydrogen-bonded beta sheet interaction, as there is between subunits within a ring, but hydrophobic interactions account for most of the intersubunit stability. The central loop, which extends into the central aqueous channel, is subject to attack by at least five enzymes and is discussed as an enzyme "passive site." |
==About this Structure== | ==About this Structure== | ||
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[[Category: Salmonella typhimurium]] | [[Category: Salmonella typhimurium]] | ||
[[Category: Single protein]] | [[Category: Single protein]] | ||
| - | [[Category: Almassy, R | + | [[Category: Almassy, R J.]] |
[[Category: Eisenberg, D.]] | [[Category: Eisenberg, D.]] | ||
| - | [[Category: Yamashita, M | + | [[Category: Yamashita, M M.]] |
[[Category: MN]] | [[Category: MN]] | ||
[[Category: ligase(amide synthetase)]] | [[Category: ligase(amide synthetase)]] | ||
| - | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 17:33:02 2008'' |
Revision as of 15:33, 21 February 2008
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REFINED ATOMIC MODEL OF GLUTAMINE SYNTHETASE AT 3.5 ANGSTROMS RESOLUTION
Overview
An atomic model of 43,692 non-hydrogen atoms has been determined for the 12-subunit enzyme glutamine synthetase from Salmonella typhimurium, by methods of x-ray diffraction including restrained least-squares atomic refinement against 65,223 unique reflections. At 3.5 A resolution the crystallographic R-factor (on 2 sigma data) is 25.8%. As reported earlier for the unrefined structure, the 12 subunits are arranged in two layers of six; at the interface of pairs of subunits within each layer, cylindrical active sites are formed by six anti-parallel beta strands contributed by one subunit and two strands by the neighboring subunit. This interpretation of the electron density map has now been supported by comparison with glutamine synthetase from Escherichia coli by the Fourier difference method. Each active site cylinder holds two Mn2+ ions, with each ion having as ligands three protein side chains and two water molecules (one water shared by both metals), as well as a histidyl side chain just beyond liganding distance. The protein ligands to Mn2+ 469 are Glu-131, Glu-212, and Glu-220; those to Mn2+ 470 are Glu-129, His-269, and Glu-357. The two layers of subunits are held together largely by the apolar COOH terminus, a helical thong, which inserts into a hydrophobic pocket formed by two neighboring subunits on the opposite ring. Also between layers, there is a hydrogen-bonded beta sheet interaction, as there is between subunits within a ring, but hydrophobic interactions account for most of the intersubunit stability. The central loop, which extends into the central aqueous channel, is subject to attack by at least five enzymes and is discussed as an enzyme "passive site."
About this Structure
2GLS is a Single protein structure of sequence from Salmonella typhimurium with as ligand. The following page contains interesting information on the relation of 2GLS with [Glutamine Synthetase]. Active as Glutamate--ammonia ligase, with EC number 6.3.1.2 Full crystallographic information is available from OCA.
Reference
Refined atomic model of glutamine synthetase at 3.5 A resolution., Yamashita MM, Almassy RJ, Janson CA, Cascio D, Eisenberg D, J Biol Chem. 1989 Oct 25;264(30):17681-90. PMID:2572586
Page seeded by OCA on Thu Feb 21 17:33:02 2008
