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| | {{STRUCTURE_1wri| PDB=1wri | SCENE= }} | | {{STRUCTURE_1wri| PDB=1wri | SCENE= }} |
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| - | '''Crystal Structure of Ferredoxin isoform II from E. arvense'''
| + | ===Crystal Structure of Ferredoxin isoform II from E. arvense=== |
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| - | ==Overview==
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| - | We have determined the crystal structure, at 1.2-A resolution, of Equisetum arvense ferredoxin isoform II (FdII), which lacks residues equivalent to Arg(39) and Glu(28) highly conserved among other ferredoxins (Fds). In other Fds these residues form an intramolecular salt bridge crucial for stabilization of the [2Fe-2S] cluster, which is disrupted upon complex formation with Fd-NADP(+) oxidoreductase (FNR) to form two intermolecular salt bridges. The overall structure of FdII resembles the known backbone structures of E. arvense isoform I (FdI) and other plant-type Fds. Dramatically, in the FdII structure a unique, alternative salt bridge is formed between Arg(22) and Glu(58). This results in a different relative orientation of the alpha-helix formed by Leu(23)-Glu(29) and eliminates the possibility of forming three of the five intermolecular salt bridges identified on formation of a complex between maize FdI and maize FNR. Mutation of FdII, informed by structural differences with FdI, showed that the alternative salt bridge and the absence of an otherwise conserved Tyr residue are important for the alternative stabilization of the FdII [2Fe-2S] cluster. We also investigated FdI and FdII electron transfer to FNR on chloroplast thylakoid membranes. The K(m) and V(max) values of FdII are similar to those of FdI, contrary to previous measurements of the reverse reaction, from FNR to Fd. The affinity between reduced FdI and oxidized FNR is much greater than that between oxidized FdI and reduced FNR, whereas this is not the case with FdII. The pH dependence of electron transfer by FdI, FdII, and an FdII mutant with FdI features was measured and further indicated that the binding mode to FNR differs between FdI and FdII. Based on this evidence, we hypothesize that binding modes with other Fd-dependent reductases may also vary between FdI and FdII. The structural differences between FdI and FdII therefore result in functional differences that may influence partitioning of electrons into different redox metabolic pathways.
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| | + | (as it appears on PubMed at http://www.pubmed.gov), where 15513928 is the PubMed ID number. |
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| | + | {{ABSTRACT_PUBMED_15513928}} |
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| | ==About this Structure== | | ==About this Structure== |
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| | [[Category: Teshima, K.]] | | [[Category: Teshima, K.]] |
| | [[Category: Electron transport]] | | [[Category: Electron transport]] |
| - | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Sat May 3 14:03:05 2008'' | + | |
| | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Mon Jul 28 00:02:31 2008'' |
Revision as of 21:02, 27 July 2008
Template:STRUCTURE 1wri
Crystal Structure of Ferredoxin isoform II from E. arvense
Template:ABSTRACT PUBMED 15513928
About this Structure
1WRI is a Single protein structure of sequence from Equisetum arvense. Full crystallographic information is available from OCA.
Reference
A structural basis of Equisetum arvense ferredoxin isoform II producing an alternative electron transfer with ferredoxin-NADP+ reductase., Kurisu G, Nishiyama D, Kusunoki M, Fujikawa S, Katoh M, Hanke GT, Hase T, Teshima K, J Biol Chem. 2005 Jan 21;280(3):2275-81. Epub 2004 Oct 28. PMID:15513928
Page seeded by OCA on Mon Jul 28 00:02:31 2008
