1chi: Difference between revisions

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STRUCTURAL STUDIES OF THE ROLES OF RESIDUES 82 AND 85 AT THE INTERACTIVE FACE OF CYTOCHROME C

OverviewOverview

A combination of structural, functional, and mutagenic experiments has been used to study the roles of the invariant Phe82 and highly conserved Leu85 residues in cytochrome c, especially with respect to the complexation interface with electron transfer partners and maintenance of the hydrophobic heme pocket. Structural analyses show that the F82Y, L85A, and F82Y/L85A mutant proteins all retain the characteristic cytochrome c fold, but that conformational alterations are introduced in the direct vicinity of the mutation sites. In particular, the additional hydroxyl group of Tyr82 is in direct spatial conflict with the side chain of Leu85 in the F82Y mutant protein, leading to rotation of the side chain of Tyr82 out toward the protein surface. This strain is relieved in the F82Y/L85A mutant protein where the phenyl ring of Tyr82 is accommodated in a conformation comparable to that of the phenylalanine normally present at this location. In addition, the available space vacated by the replacement of Leu85 with an alanine allows for the inclusion of two new internal water molecules, one of which is bound to Tyr82 and the other to Arg13. In contrast, in the L85A mutant protein, no internal water molecules are observed in this exclusively hydrophobic pocket, which is partially filled by shifts in nearby side chains. Overall, the conformational changes observed result from the optimization of side chain packing to reflect the spatial requirements of new side chains, the minimization of both vacant internal space and the solvent exposure of hydrophobic groups, and the attainment of maximal hydrogen bonding between available polar groups.(ABSTRACT TRUNCATED AT 250 WORDS)

About this StructureAbout this Structure

1CHI is a Single protein structure of sequence from Saccharomyces cerevisiae with , and as ligands. Full crystallographic information is available from OCA.

ReferenceReference

Structural studies of the roles of residues 82 and 85 at the interactive face of cytochrome c., Lo TP, Guillemette JG, Louie GV, Smith M, Brayer GD, Biochemistry. 1995 Jan 10;34(1):163-71. PMID:7819192

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OCA

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-[[Image:1chi.gif|left|200px]]<br /><applet load="1chi" size="450" color="white" frame="true" align="right" spinBox="true"
+[[Image:1chi.gif|left|200px]]<br /><applet load="1chi" size="350" color="white" frame="true" align="right" spinBox="true"
 caption="1chi, resolution 2.0&Aring;" />
 '''STRUCTURAL STUDIES OF THE ROLES OF RESIDUES 82 AND 85 AT THE INTERACTIVE FACE OF CYTOCHROME C'''<br />
 ==Overview==
-A combination of structural, functional, and mutagenic experiments has, been used to study the roles of the invariant Phe82 and highly conserved, Leu85 residues in cytochrome c, especially with respect to the, complexation interface with electron transfer partners and maintenance of, the hydrophobic heme pocket. Structural analyses show that the F82Y, L85A, and F82Y/L85A mutant proteins all retain the characteristic cytochrome c, fold, but that conformational alterations are introduced in the direct, vicinity of the mutation sites. In particular, the additional hydroxyl, group of Tyr82 is in direct spatial conflict with the side chain of Leu85, in the F82Y mutant protein, leading to rotation of the side chain of Tyr82, out toward the protein surface. This strain is relieved in the F82Y/L85A, mutant protein where the phenyl ring of Tyr82 is accommodated in a, conformation comparable to that of the phenylalanine normally present at, this location. In addition, the available space vacated by the replacement, of Leu85 with an alanine allows for the inclusion of two new internal, water molecules, one of which is bound to Tyr82 and the other to Arg13. In, contrast, in the L85A mutant protein, no internal water molecules are, observed in this exclusively hydrophobic pocket, which is partially filled, by shifts in nearby side chains. Overall, the conformational changes, observed result from the optimization of side chain packing to reflect the, spatial requirements of new side chains, the minimization of both vacant, internal space and the solvent exposure of hydrophobic groups, and the, attainment of maximal hydrogen bonding between available polar, groups.(ABSTRACT TRUNCATED AT 250 WORDS)
+A combination of structural, functional, and mutagenic experiments has been used to study the roles of the invariant Phe82 and highly conserved Leu85 residues in cytochrome c, especially with respect to the complexation interface with electron transfer partners and maintenance of the hydrophobic heme pocket. Structural analyses show that the F82Y, L85A, and F82Y/L85A mutant proteins all retain the characteristic cytochrome c fold, but that conformational alterations are introduced in the direct vicinity of the mutation sites. In particular, the additional hydroxyl group of Tyr82 is in direct spatial conflict with the side chain of Leu85 in the F82Y mutant protein, leading to rotation of the side chain of Tyr82 out toward the protein surface. This strain is relieved in the F82Y/L85A mutant protein where the phenyl ring of Tyr82 is accommodated in a conformation comparable to that of the phenylalanine normally present at this location. In addition, the available space vacated by the replacement of Leu85 with an alanine allows for the inclusion of two new internal water molecules, one of which is bound to Tyr82 and the other to Arg13. In contrast, in the L85A mutant protein, no internal water molecules are observed in this exclusively hydrophobic pocket, which is partially filled by shifts in nearby side chains. Overall, the conformational changes observed result from the optimization of side chain packing to reflect the spatial requirements of new side chains, the minimization of both vacant internal space and the solvent exposure of hydrophobic groups, and the attainment of maximal hydrogen bonding between available polar groups.(ABSTRACT TRUNCATED AT 250 WORDS)
 ==About this Structure==
-CHI is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Saccharomyces_cerevisiae Saccharomyces cerevisiae] with SO4, HEM and TML as [http://en.wikipedia.org/wiki/ligands ligands]. Full crystallographic information is available from [http://ispc.weizmann.ac.il/oca-bin/ocashort?id=1CHI OCA].
+CHI is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Saccharomyces_cerevisiae Saccharomyces cerevisiae] with <scene name='pdbligand=SO4:'>SO4</scene>, <scene name='pdbligand=HEM:'>HEM</scene> and <scene name='pdbligand=TML:'>TML</scene> as [http://en.wikipedia.org/wiki/ligands ligands]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1CHI OCA].
 ==Reference==
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 [[Category: Saccharomyces cerevisiae]]
 [[Category: Single protein]]
-[[Category: Brayer, G.D.]]
+[[Category: Brayer, G D.]]
-[[Category: Lo, T.P.]]
+[[Category: Lo, T P.]]
 [[Category: HEM]]
 [[Category: SO4]]
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 [[Category: electron transport(heme protein)]]
-''Page seeded by [http://ispc.weizmann.ac.il/oca OCA ] on Tue Nov 20 12:27:37 2007''
+''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 12:06:08 2008''