1cp2

From Proteopedia

Revision as of 13:54, 5 November 2007

NITROGENASE IRON PROTEIN FROM CLOSTRIDIUM PASTEURIANUM

Overview

The nitrogenase iron (Fe) protein performs multiple functions during, biological nitrogen fixation, including mediating the mechanistically, essential coupling between ATP hydrolysis and electron transfer to the, nitrogenase molybdenum iron (MoFe) protein during substrate reduction, and, participating in the biosynthesis and insertion of the FeMo-cofactor into, the MoFe-protein. To establish a structural framework for addressing the, diverse functions of Fe-protein, crystal structures of the Fe-proteins, from Azotobacter vinelandii and Clostridium pasteurianum have been, determined at resolutions of 2.2 A and 1.93 A, respectively. These two, Fe-proteins are among the more diverse in terms of amino acid sequence and, biochemical properties. As described initially for the A. vinelandii, Fe-protein in a different crystal form at 2.9 A resolution, each subunit, of the dimeric Fe-protein adopts a polypeptide fold related to other, mononucleotide-binding proteins such as G-proteins, with the two subunits, bridged by a 4Fe:4S cluster. The overall similarities in the subunit fold, and dimer arrangement observed in the structures of the A. vinelandii and, C. pasteurianum Fe-proteins indicate that they are representative of the, conformation of free Fe-protein that is not in complex with nucleotide or, the MoFe-protein. Residues in the cluster and nucleotide-binding sites are, linked by a network of conserved hydrogen bonds, salt-bridges and water, molecules that may conformationally couple these regions. Significant, variability is observed in localized regions, especially near the 4Fe:4S, cluster and the MoFe-protein binding surface, that change conformation, upon formation of the ADP.AlF4- stabilized complex with the MoFe-protein., A core of 140 conserved residues is identified in an alignment of 59, Fe-protein sequences that may be useful for the identification of, homologous proteins with functions comparable to that of Fe-protein in, non-nitrogen fixing systems.

About this Structure

1CP2 is a Single protein structure of sequence from Clostridium pasteurianum with SF4 as ligand. Active as Nitrogenase, with EC number 1.18.6.1 Structure known Active Site: FES. Full crystallographic information is available from OCA.

Reference

Conformational variability in structures of the nitrogenase iron proteins from Azotobacter vinelandii and Clostridium pasteurianum., Schlessman JL, Woo D, Joshua-Tor L, Howard JB, Rees DC, J Mol Biol. 1998 Jul 24;280(4):669-85. PMID:9677296

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