1g21
From Proteopedia
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'''MGATP-BOUND AND NUCLEOTIDE-FREE STRUCTURES OF A NITROGENASE PROTEIN COMPLEX BETWEEN LEU127DEL-FE PROTEIN AND THE MOFE PROTEIN''' | '''MGATP-BOUND AND NUCLEOTIDE-FREE STRUCTURES OF A NITROGENASE PROTEIN COMPLEX BETWEEN LEU127DEL-FE PROTEIN AND THE MOFE PROTEIN''' | ||
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[[Category: Seefeldt, L C.]] | [[Category: Seefeldt, L C.]] | ||
[[Category: 4fe-4]] | [[Category: 4fe-4]] | ||
| - | [[Category: | + | [[Category: Fe protein]] |
| - | [[Category: | + | [[Category: Femo cofactor]] |
| - | [[Category: | + | [[Category: Moefe protein]] |
| - | [[Category: | + | [[Category: Nitrogen-fixation]] |
| - | [[Category: | + | [[Category: P-cluster]] |
| - | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Fri May 2 17:02:13 2008'' | |
| - | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on | + | |
Revision as of 14:02, 2 May 2008
MGATP-BOUND AND NUCLEOTIDE-FREE STRUCTURES OF A NITROGENASE PROTEIN COMPLEX BETWEEN LEU127DEL-FE PROTEIN AND THE MOFE PROTEIN
Overview
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
1G21 is a Protein complex structure of sequences from Azotobacter vinelandii. Full crystallographic information is available from OCA.
Reference
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 Page seeded by OCA on Fri May 2 17:02:13 2008
