1nla
From Proteopedia
(New page: 200px<br /><applet load="1nla" size="450" color="white" frame="true" align="right" spinBox="true" caption="1nla" /> '''Solution Structure of Switch Arc, a Mutant w...) |
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'''Solution Structure of Switch Arc, a Mutant with 3(10) Helices Replacing a Wild-Type Beta-Ribbon'''<br /> | '''Solution Structure of Switch Arc, a Mutant with 3(10) Helices Replacing a Wild-Type Beta-Ribbon'''<br /> | ||
==Overview== | ==Overview== | ||
| - | Adjacent N11L and L12N mutations in the antiparallel beta-ribbon of Arc | + | Adjacent N11L and L12N mutations in the antiparallel beta-ribbon of Arc repressor result in dramatic changes in local structure in which each beta-strand is replaced by a right-handed helix. The full solution structure of this "switch" Arc mutant shows that irregular 3(10) helices compose the new secondary structure. This structural metamorphosis conserves the number of main-chain and side-chain to main-chain hydrogen bonds and the number of fully buried core residues. Apart from a slight widening of the interhelical angle between alpha-helices A and B and changes in side-chain conformation of a few core residues in Arc, no large-scale structural adjustments in the remainder of the protein are necessary to accommodate the ribbon-to-helix change. Nevertheless, some changes in hydrogen-exchange rates are observed, even in regions that have very similar structures in the two proteins. The surface of switch Arc is packed poorly compared to wild-type, leading to approximately 1000A(2) of additional solvent-accessible surface area, and the N termini of the 3(10) helices make unfavorable head-to-head electrostatic interactions. These structural features account for the positive m value and salt dependence of the ribbon-to-helix transition in Arc-N11L, a variant that can adopt either the mutant or wild-type structures. The tertiary fold is capped in different ways in switch and wild-type Arc, showing how stepwise evolutionary transformations can arise through small changes in amino acid sequence. |
==About this Structure== | ==About this Structure== | ||
| - | 1NLA is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Yersinia_phage_py54 Yersinia phage py54]. Full crystallographic information is available from [http:// | + | 1NLA is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Yersinia_phage_py54 Yersinia phage py54]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1NLA OCA]. |
==Reference== | ==Reference== | ||
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[[Category: Single protein]] | [[Category: Single protein]] | ||
[[Category: Yersinia phage py54]] | [[Category: Yersinia phage py54]] | ||
| - | [[Category: Cordes, M | + | [[Category: Cordes, M H.]] |
| - | [[Category: McKnight, C | + | [[Category: McKnight, C J.]] |
| - | [[Category: Sauer, R | + | [[Category: Sauer, R T.]] |
| - | [[Category: Walsh, N | + | [[Category: Walsh, N P.]] |
[[Category: 3(10) helix]] | [[Category: 3(10) helix]] | ||
[[Category: beta-ribbon]] | [[Category: beta-ribbon]] | ||
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[[Category: structural switching]] | [[Category: structural switching]] | ||
| - | ''Page seeded by [http:// | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 14:07:17 2008'' |
Revision as of 12:07, 21 February 2008
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Solution Structure of Switch Arc, a Mutant with 3(10) Helices Replacing a Wild-Type Beta-Ribbon
Overview
Adjacent N11L and L12N mutations in the antiparallel beta-ribbon of Arc repressor result in dramatic changes in local structure in which each beta-strand is replaced by a right-handed helix. The full solution structure of this "switch" Arc mutant shows that irregular 3(10) helices compose the new secondary structure. This structural metamorphosis conserves the number of main-chain and side-chain to main-chain hydrogen bonds and the number of fully buried core residues. Apart from a slight widening of the interhelical angle between alpha-helices A and B and changes in side-chain conformation of a few core residues in Arc, no large-scale structural adjustments in the remainder of the protein are necessary to accommodate the ribbon-to-helix change. Nevertheless, some changes in hydrogen-exchange rates are observed, even in regions that have very similar structures in the two proteins. The surface of switch Arc is packed poorly compared to wild-type, leading to approximately 1000A(2) of additional solvent-accessible surface area, and the N termini of the 3(10) helices make unfavorable head-to-head electrostatic interactions. These structural features account for the positive m value and salt dependence of the ribbon-to-helix transition in Arc-N11L, a variant that can adopt either the mutant or wild-type structures. The tertiary fold is capped in different ways in switch and wild-type Arc, showing how stepwise evolutionary transformations can arise through small changes in amino acid sequence.
About this Structure
1NLA is a Single protein structure of sequence from Yersinia phage py54. Full crystallographic information is available from OCA.
Reference
Solution structure of switch Arc, a mutant with 3(10) helices replacing a wild-type beta-ribbon., Cordes MH, Walsh NP, McKnight CJ, Sauer RT, J Mol Biol. 2003 Feb 21;326(3):899-909. PMID:12581649
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