1bne: Difference between revisions

Revision as of 12:57, 21 February 2008

BARNASE A43C/S80C DISULFIDE MUTANT

OverviewOverview

In this series of papers, we examine the effects of introducing disulfide bonds on the properties, structure and thermodynamics of a small globular protein, barnase. Three mutants have been made, in each of which a single crosslink confers different properties. Two of the disulfide bonds, between residues 43 and 80 (43-80) and between residues 85 and 102 (85-102), stabilise the protein, relative to both wild-type and the corresponding (reduced) dithiol forms: 85-102 is more stable than predicted from the entropic destabilisation of the unfolded state; 43-80 is less stable than predicted. The third disulfide bond, between residues 70 and 92 (70-92) destabilises the protein relative to both wild-type and the corresponding dithiol form, implying significant disruption of the folded protein on formation of the disulfide bond. Crystal structures of the three mutant proteins have been solved. All three proteins have essentially the same fold as wild-type, but with left-handed disulfide bonds, which have dihedral geometries that have not been observed in naturally occurring disulfides. In the very stable mutant 85-102, there is no significant difference between the mutant and wild-type structures: these data do not explain the large stability of this protein. The disulfide bond at 43-80 induces small structural rearrangements close to the site of the disulfide bond, associated with some local disorder: the crosslink appears to decrease the stability of the native form of the protein. The destabilising disulfide bond at 70-92 induces considerable structural change, with displacement of a loop and consequent disruption of a stabilising salt-bridge. Our studies do not support the view that the conformation of the disulfide bond is crucial in determining the stability of the mutant proteins.

About this StructureAbout this Structure

1BNE is a Single protein structure of sequence from Bacillus amyloliquefaciens. Full crystallographic information is available from OCA.

ReferenceReference

Disulfide mutants of barnase. I: Changes in stability and structure assessed by biophysical methods and X-ray crystallography., Clarke J, Henrick K, Fersht AR, J Mol Biol. 1995 Oct 27;253(3):493-504. PMID:7473729

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-[[Image:1bne.gif|left|200px]]<br /><applet load="1bne" size="450" color="white" frame="true" align="right" spinBox="true"
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 caption="1bne, resolution 2.1&Aring;" />
 '''BARNASE A43C/S80C DISULFIDE MUTANT'''<br />
 ==Overview==
-In this series of papers, we examine the effects of introducing disulfide, bonds on the properties, structure and thermodynamics of a small globular, protein, barnase. Three mutants have been made, in each of which a single, crosslink confers different properties. Two of the disulfide bonds, between residues 43 and 80 (43-80) and between residues 85 and 102, (85-102), stabilise the protein, relative to both wild-type and the, corresponding (reduced) dithiol forms: 85-102 is more stable than, predicted from the entropic destabilisation of the unfolded state; 43-80, is less stable than predicted. The third disulfide bond, between residues, 70 and 92 (70-92) destabilises the protein relative to both wild-type and, the corresponding dithiol form, implying significant disruption of the, folded protein on formation of the disulfide bond. Crystal structures of, the three mutant proteins have been solved. All three proteins have, essentially the same fold as wild-type, but with left-handed disulfide, bonds, which have dihedral geometries that have not been observed in, naturally occurring disulfides. In the very stable mutant 85-102, there is, no significant difference between the mutant and wild-type structures:, these data do not explain the large stability of this protein. The, disulfide bond at 43-80 induces small structural rearrangements close to, the site of the disulfide bond, associated with some local disorder: the, crosslink appears to decrease the stability of the native form of the, protein. The destabilising disulfide bond at 70-92 induces considerable, structural change, with displacement of a loop and consequent disruption, of a stabilising salt-bridge. Our studies do not support the view that the, conformation of the disulfide bond is crucial in determining the stability, of the mutant proteins.
+In this series of papers, we examine the effects of introducing disulfide bonds on the properties, structure and thermodynamics of a small globular protein, barnase. Three mutants have been made, in each of which a single crosslink confers different properties. Two of the disulfide bonds, between residues 43 and 80 (43-80) and between residues 85 and 102 (85-102), stabilise the protein, relative to both wild-type and the corresponding (reduced) dithiol forms: 85-102 is more stable than predicted from the entropic destabilisation of the unfolded state; 43-80 is less stable than predicted. The third disulfide bond, between residues 70 and 92 (70-92) destabilises the protein relative to both wild-type and the corresponding dithiol form, implying significant disruption of the folded protein on formation of the disulfide bond. Crystal structures of the three mutant proteins have been solved. All three proteins have essentially the same fold as wild-type, but with left-handed disulfide bonds, which have dihedral geometries that have not been observed in naturally occurring disulfides. In the very stable mutant 85-102, there is no significant difference between the mutant and wild-type structures: these data do not explain the large stability of this protein. The disulfide bond at 43-80 induces small structural rearrangements close to the site of the disulfide bond, associated with some local disorder: the crosslink appears to decrease the stability of the native form of the protein. The destabilising disulfide bond at 70-92 induces considerable structural change, with displacement of a loop and consequent disruption of a stabilising salt-bridge. Our studies do not support the view that the conformation of the disulfide bond is crucial in determining the stability of the mutant proteins.
 ==About this Structure==
-BNE is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Bacillus_amyloliquefaciens Bacillus amyloliquefaciens]. Full crystallographic information is available from [http://ispc.weizmann.ac.il/oca-bin/ocashort?id=1BNE OCA].
+BNE is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Bacillus_amyloliquefaciens Bacillus amyloliquefaciens]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1BNE OCA].
 ==Reference==
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 [[Category: Single protein]]
 [[Category: Clarke, J.]]
-[[Category: Fersht, A.R.]]
+[[Category: Fersht, A R.]]
 [[Category: Henrick, K.]]
 [[Category: endonuclease]]
-''Page seeded by [http://ispc.weizmann.ac.il/oca OCA ] on Tue Nov 20 11:46:18 2007''
+''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 11:57:03 2008''