1g21: Difference between revisions
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[[Image:1g21.gif|left|200px]]<br /><applet load="1g21" size=" | [[Image:1g21.gif|left|200px]]<br /><applet load="1g21" size="350" color="white" frame="true" align="right" spinBox="true" | ||
caption="1g21, resolution 3.0Å" /> | caption="1g21, resolution 3.0Å" /> | ||
'''MGATP-BOUND AND NUCLEOTIDE-FREE STRUCTURES OF A NITROGENASE PROTEIN COMPLEX BETWEEN LEU127DEL-FE PROTEIN AND THE MOFE PROTEIN'''<br /> | '''MGATP-BOUND AND NUCLEOTIDE-FREE STRUCTURES OF A NITROGENASE PROTEIN COMPLEX BETWEEN LEU127DEL-FE PROTEIN AND THE MOFE PROTEIN'''<br /> | ||
==Overview== | ==Overview== | ||
A mutant form of the nitrogenase iron protein with a deletion of residue | A mutant form of the nitrogenase iron protein with a deletion of residue Leu 127, located in the switch II region of the nucleotide binding site, forms a tight, inactive complex with the nitrogenase molybdenum iron (MoFe) protein in the absence of nucleotide. The structure of this complex generated with proteins from Azotobacter vinelandii (designated the L127Delta-Av2-Av1 complex) has been crystallographically determined in the absence of nucleotide at 2.2 A resolution and with bound MgATP (introduced by soaking) at 3.0 A resolution. As observed in the structure of the complex between the wild-type A. vinelandii nitrogenase proteins stabilized with ADP.AlF(4-), the most significant conformational changes in the L127Delta complex occur in the Fe-protein component. While the interactions at the interface between the MoFe-protein and Fe-proteins are conserved in the two complexes, significant differences are evident at the subunit-subunit interface of the dimeric Fe-proteins, with the L127Delta-Av2 structure having a more open conformation than the wild-type Av2 in the complex stabilized by ADP.AlF(4-). Addition of MgATP to the L127Delta-Av2-Av1 complex results in a further increase in the separation between Fe-protein subunits so that the structure more closely resembles that of the wild-type, nucleotide-free, uncomplexed Fe-protein, rather than the Fe-protein conformation in the ADP.AlF(4-) complex. The L127Delta mutation precludes key interactions between the Fe-protein and nucleotide, especially, but not exclusively, in the region corresponding to the switch II region of G-proteins, where the deletion constrains Gly 128 and Asp 129 from forming hydrogen bonds to the gamma-phosphate and activating water for attack on this group, respectively. These alterations account for the inability of this mutant to support mechanistically productive ATP hydrolysis. The ability of the L127Delta-Av2-Av1 complex to bind MgATP demonstrates that dissociation of the nitrogenase complex is not required for nucleotide binding. | ||
==About this Structure== | ==About this Structure== | ||
1G21 is a [http://en.wikipedia.org/wiki/Protein_complex Protein complex] structure of sequences from [http://en.wikipedia.org/wiki/Azotobacter_vinelandii Azotobacter vinelandii] with MG, CA, SF4, ATP, HCA, CFM and CLF as [http://en.wikipedia.org/wiki/ligands ligands]. Active as [http://en.wikipedia.org/wiki/Nitrogenase Nitrogenase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=1.18.6.1 1.18.6.1] Full crystallographic information is available from [http:// | 1G21 is a [http://en.wikipedia.org/wiki/Protein_complex Protein complex] structure of sequences from [http://en.wikipedia.org/wiki/Azotobacter_vinelandii Azotobacter vinelandii] with <scene name='pdbligand=MG:'>MG</scene>, <scene name='pdbligand=CA:'>CA</scene>, <scene name='pdbligand=SF4:'>SF4</scene>, <scene name='pdbligand=ATP:'>ATP</scene>, <scene name='pdbligand=HCA:'>HCA</scene>, <scene name='pdbligand=CFM:'>CFM</scene> and <scene name='pdbligand=CLF:'>CLF</scene> as [http://en.wikipedia.org/wiki/ligands ligands]. Active as [http://en.wikipedia.org/wiki/Nitrogenase Nitrogenase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=1.18.6.1 1.18.6.1] Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1G21 OCA]. | ||
==Reference== | ==Reference== | ||
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[[Category: Nitrogenase]] | [[Category: Nitrogenase]] | ||
[[Category: Protein complex]] | [[Category: Protein complex]] | ||
[[Category: Chiu, H | [[Category: Chiu, H J.]] | ||
[[Category: Howard, J | [[Category: Howard, J B.]] | ||
[[Category: Lanzilotta, W | [[Category: Lanzilotta, W N.]] | ||
[[Category: Peters, J | [[Category: Peters, J W.]] | ||
[[Category: Rees, D | [[Category: Rees, D C.]] | ||
[[Category: Ryle, M | [[Category: Ryle, M J.]] | ||
[[Category: Seefeldt, L | [[Category: Seefeldt, L C.]] | ||
[[Category: ATP]] | [[Category: ATP]] | ||
[[Category: CA]] | [[Category: CA]] | ||
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[[Category: p-cluster]] | [[Category: p-cluster]] | ||
''Page seeded by [http:// | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 12:45:11 2008'' | ||
Revision as of 13:45, 21 February 2008
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MGATP-BOUND AND NUCLEOTIDE-FREE STRUCTURES OF A NITROGENASE PROTEIN COMPLEX BETWEEN LEU127DEL-FE PROTEIN AND THE MOFE PROTEIN
OverviewOverview
A mutant form of the nitrogenase iron protein with a deletion of residue Leu 127, located in the switch II region of the nucleotide binding site, forms a tight, inactive complex with the nitrogenase molybdenum iron (MoFe) protein in the absence of nucleotide. The structure of this complex generated with proteins from Azotobacter vinelandii (designated the L127Delta-Av2-Av1 complex) has been crystallographically determined in the absence of nucleotide at 2.2 A resolution and with bound MgATP (introduced by soaking) at 3.0 A resolution. As observed in the structure of the complex between the wild-type A. vinelandii nitrogenase proteins stabilized with ADP.AlF(4-), the most significant conformational changes in the L127Delta complex occur in the Fe-protein component. While the interactions at the interface between the MoFe-protein and Fe-proteins are conserved in the two complexes, significant differences are evident at the subunit-subunit interface of the dimeric Fe-proteins, with the L127Delta-Av2 structure having a more open conformation than the wild-type Av2 in the complex stabilized by ADP.AlF(4-). Addition of MgATP to the L127Delta-Av2-Av1 complex results in a further increase in the separation between Fe-protein subunits so that the structure more closely resembles that of the wild-type, nucleotide-free, uncomplexed Fe-protein, rather than the Fe-protein conformation in the ADP.AlF(4-) complex. The L127Delta mutation precludes key interactions between the Fe-protein and nucleotide, especially, but not exclusively, in the region corresponding to the switch II region of G-proteins, where the deletion constrains Gly 128 and Asp 129 from forming hydrogen bonds to the gamma-phosphate and activating water for attack on this group, respectively. These alterations account for the inability of this mutant to support mechanistically productive ATP hydrolysis. The ability of the L127Delta-Av2-Av1 complex to bind MgATP demonstrates that dissociation of the nitrogenase complex is not required for nucleotide binding.
About this StructureAbout this Structure
1G21 is a Protein complex structure of sequences from Azotobacter vinelandii with , , , , , and as ligands. Active as Nitrogenase, with EC number 1.18.6.1 Full crystallographic information is available from OCA.
ReferenceReference
MgATP-Bound and nucleotide-free structures of a nitrogenase protein complex between the Leu 127 Delta-Fe-protein and the MoFe-protein., Chiu H, Peters JW, Lanzilotta WN, Ryle MJ, Seefeldt LC, Howard JB, Rees DC, Biochemistry. 2001 Jan 23;40(3):641-50. PMID:11170380
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