1frl: Difference between revisions

Revision as of 13:41, 21 February 2008

AZOTOBACTER VINELANDII FERREDOXIN I: ALTERATION OF INDIVIDUAL SURFACE CHARGES AND THE [4FE-4S] CLUSTER REDUCTION POTENTIAL

OverviewOverview

The structures of Azotobacter vinelandii ferredoxin I (AvFdI) and Peptococcus aerogenes ferredoxin (PaFd), near their analogous [4e-4S]2+/+ clusters, are highly conserved (Backes, G., Mino, Y., Loehr, T.M., Meyer, T.E., Cusanovich, M.A., Sweeney, W.V., Adman, E.T., and Sanders-Loehr, J. (1991) J. Am. Chem. Soc. 11, 2055-2064). Despite these similarities, the reduction potential (E0') of the AvFdI [4Fe-4S]2+/+ cluster is more than 200 mV more negative than that of PaFd. We have tested the contribution that individual amino acid residues make to the control of E0' by converting residues in AvFdI into the corresponding residue in PaFd. Four mutations involved substitutions of negatively charged surface residues with neutral residues and two involved substitution of buried hydrophobic residues. All AvFdI variants were characterized by x-ray crystallography, absorption, CD, EPR, and 1H NMR spectroscopies and by electrochemical methods. For the F25I mutation, significant structural changes occurred that affected the EPR and 1H NMR spectroscopic properties of AvFdI and had a minor influence on E0'. For all other mutations there were no changes in reduction potential. Thus we conclude, that variations in charged surface residues do not account for the observed differences in E0' between the analogous [4Fe-4S]2+/+ cluster of PaFd and AvFdI. These differences are therefore most likely to be due to differences in solvent accessibility.

About this StructureAbout this Structure

1FRL is a Single protein structure of sequence from Azotobacter vinelandii with and as ligands. Full crystallographic information is available from OCA.

ReferenceReference

Azotobacter vinelandii ferredoxin I. Alteration of individual surface charges and the [4FE-4S]2+/+ cluster reduction potential., Shen B, Jollie DR, Stout CD, Diller TC, Armstrong FA, Gorst CM, La Mar GN, Stephens PJ, Burgess BK, J Biol Chem. 1994 Mar 18;269(11):8564-75. PMID:8132582

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OCA

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-[[Image:1frl.gif|left|200px]]<br /><applet load="1frl" size="450" color="white" frame="true" align="right" spinBox="true"
+[[Image:1frl.gif|left|200px]]<br /><applet load="1frl" size="350" color="white" frame="true" align="right" spinBox="true"
 caption="1frl, resolution 2.3&Aring;" />
 '''AZOTOBACTER VINELANDII FERREDOXIN I: ALTERATION OF INDIVIDUAL SURFACE CHARGES AND THE [4FE-4S] CLUSTER REDUCTION POTENTIAL'''<br />
 ==Overview==
-The structures of Azotobacter vinelandii ferredoxin I (AvFdI) and, Peptococcus aerogenes ferredoxin (PaFd), near their analogous [4e-4S]2+/+, clusters, are highly conserved (Backes, G., Mino, Y., Loehr, T.M., Meyer, T.E., Cusanovich, M.A., Sweeney, W.V., Adman, E.T., and Sanders-Loehr, J., (1991) J. Am. Chem. Soc. 11, 2055-2064). Despite these similarities, the, reduction potential (E0') of the AvFdI [4Fe-4S]2+/+ cluster is more than, 200 mV more negative than that of PaFd. We have tested the contribution, that individual amino acid residues make to the control of E0' by, converting residues in AvFdI into the corresponding residue in PaFd. Four, mutations involved substitutions of negatively charged surface residues, with neutral residues and two involved substitution of buried hydrophobic, residues. All AvFdI variants were characterized by x-ray crystallography, absorption, CD, EPR, and 1H NMR spectroscopies and by electrochemical, methods. For the F25I mutation, significant structural changes occurred, that affected the EPR and 1H NMR spectroscopic properties of AvFdI and had, a minor influence on E0'. For all other mutations there were no changes in, reduction potential. Thus we conclude, that variations in charged surface, residues do not account for the observed differences in E0' between the, analogous [4Fe-4S]2+/+ cluster of PaFd and AvFdI. These differences are, therefore most likely to be due to differences in solvent accessibility.
+The structures of Azotobacter vinelandii ferredoxin I (AvFdI) and Peptococcus aerogenes ferredoxin (PaFd), near their analogous [4e-4S]2+/+ clusters, are highly conserved (Backes, G., Mino, Y., Loehr, T.M., Meyer, T.E., Cusanovich, M.A., Sweeney, W.V., Adman, E.T., and Sanders-Loehr, J. (1991) J. Am. Chem. Soc. 11, 2055-2064). Despite these similarities, the reduction potential (E0') of the AvFdI [4Fe-4S]2+/+ cluster is more than 200 mV more negative than that of PaFd. We have tested the contribution that individual amino acid residues make to the control of E0' by converting residues in AvFdI into the corresponding residue in PaFd. Four mutations involved substitutions of negatively charged surface residues with neutral residues and two involved substitution of buried hydrophobic residues. All AvFdI variants were characterized by x-ray crystallography, absorption, CD, EPR, and 1H NMR spectroscopies and by electrochemical methods. For the F25I mutation, significant structural changes occurred that affected the EPR and 1H NMR spectroscopic properties of AvFdI and had a minor influence on E0'. For all other mutations there were no changes in reduction potential. Thus we conclude, that variations in charged surface residues do not account for the observed differences in E0' between the analogous [4Fe-4S]2+/+ cluster of PaFd and AvFdI. These differences are therefore most likely to be due to differences in solvent accessibility.
 ==About this Structure==
-FRL is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Azotobacter_vinelandii Azotobacter vinelandii] with SF4 and F3S as [http://en.wikipedia.org/wiki/ligands ligands]. Full crystallographic information is available from [http://ispc.weizmann.ac.il/oca-bin/ocashort?id=1FRL OCA].
+FRL is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Azotobacter_vinelandii Azotobacter vinelandii] with <scene name='pdbligand=SF4:'>SF4</scene> and <scene name='pdbligand=F3S:'>F3S</scene> as [http://en.wikipedia.org/wiki/ligands ligands]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1FRL OCA].
 ==Reference==
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 [[Category: Azotobacter vinelandii]]
 [[Category: Single protein]]
-[[Category: Stout, C.D.]]
+[[Category: Stout, C D.]]
 [[Category: F3S]]
 [[Category: SF4]]
 [[Category: electron transport]]
-''Page seeded by [http://ispc.weizmann.ac.il/oca OCA ] on Tue Nov 20 15:11:57 2007''
+''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 12:41:52 2008''