Source:http://linkedlifedata.com/resource/pubmed/id/11170380
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rdf:type | |
lifeskim:mentions | |
pubmed:issue |
3
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pubmed:dateCreated |
2001-2-22
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pubmed:databankReference | |
pubmed:abstractText |
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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pubmed:grant | |
pubmed:language |
eng
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pubmed:journal | |
pubmed:citationSubset |
IM
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pubmed:chemical | |
pubmed:status |
MEDLINE
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pubmed:month |
Jan
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pubmed:issn |
0006-2960
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pubmed:author | |
pubmed:issnType |
Print
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pubmed:day |
23
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pubmed:volume |
40
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pubmed:owner |
NLM
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pubmed:authorsComplete |
Y
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pubmed:pagination |
641-50
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pubmed:dateRevised |
2007-11-14
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pubmed:meshHeading |
pubmed-meshheading:11170380-Adenosine Triphosphate,
pubmed-meshheading:11170380-Azotobacter vinelandii,
pubmed-meshheading:11170380-Binding Sites,
pubmed-meshheading:11170380-Crystallography, X-Ray,
pubmed-meshheading:11170380-Electron Transport,
pubmed-meshheading:11170380-Hydrolysis,
pubmed-meshheading:11170380-Leucine,
pubmed-meshheading:11170380-Molybdoferredoxin,
pubmed-meshheading:11170380-Mutagenesis, Site-Directed,
pubmed-meshheading:11170380-Nitrogenase,
pubmed-meshheading:11170380-Protein Conformation,
pubmed-meshheading:11170380-Protein Structure, Secondary,
pubmed-meshheading:11170380-Sequence Deletion
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pubmed:year |
2001
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pubmed:articleTitle |
MgATP-Bound and nucleotide-free structures of a nitrogenase protein complex between the Leu 127 Delta-Fe-protein and the MoFe-protein.
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pubmed:affiliation |
Division of Chemistry and Chemical Engineering, Mail Code 147-75CH, California Institute of Technology, Pasadena, California 91125, USA.
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pubmed:publicationType |
Journal Article,
Research Support, U.S. Gov't, P.H.S.,
Research Support, U.S. Gov't, Non-P.H.S.
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