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1g20

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{{STRUCTURE_1g20| PDB=1g20 | SCENE= }}
{{STRUCTURE_1g20| PDB=1g20 | SCENE= }}
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'''MGATP-BOUND AND NUCLEOTIDE-FREE STRUCTURES OF A NITROGENASE PROTEIN COMPLEX BETWEEN LEU127DEL-FE PROTEIN AND THE MOFE PROTEIN'''
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===MGATP-BOUND AND NUCLEOTIDE-FREE STRUCTURES OF A NITROGENASE PROTEIN COMPLEX BETWEEN LEU127DEL-FE PROTEIN AND THE MOFE PROTEIN===
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==Overview==
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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.
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(as it appears on PubMed at http://www.pubmed.gov), where 11170380 is the PubMed ID number.
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{{ABSTRACT_PUBMED_11170380}}
==About this Structure==
==About this Structure==
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[[Category: Nitrogen-fixation]]
[[Category: Nitrogen-fixation]]
[[Category: P-cluster and femo cofactor]]
[[Category: P-cluster and femo cofactor]]
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''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Tue Jul 1 04:17:13 2008''

Revision as of 01:17, 1 July 2008

Image:1g20.png

Template:STRUCTURE 1g20

MGATP-BOUND AND NUCLEOTIDE-FREE STRUCTURES OF A NITROGENASE PROTEIN COMPLEX BETWEEN LEU127DEL-FE PROTEIN AND THE MOFE PROTEIN

Template:ABSTRACT PUBMED 11170380

About this Structure

1G20 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

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