1t8a: Difference between revisions

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[[Image:1t8a.jpg|left|200px]]
{{Seed}}
[[Image:1t8a.png|left|200px]]


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{{STRUCTURE_1t8a|  PDB=1t8a  |  SCENE=  }}  
{{STRUCTURE_1t8a|  PDB=1t8a  |  SCENE=  }}  


'''USE OF SEQUENCE DUPLICATION TO ENGINEER A LIGAND-TRIGGERED LONG-DISTANCE MOLECULAR SWITCH IN T4 LYSOSYME'''
===USE OF SEQUENCE DUPLICATION TO ENGINEER A LIGAND-TRIGGERED LONG-DISTANCE MOLECULAR SWITCH IN T4 LYSOSYME===




==Overview==
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We have designed a molecular switch in a T4 lysozyme construct that controls a large-scale translation of a duplicated helix. As shown by crystal structures of the construct with the switch on and off, the conformational change is triggered by the binding of a ligand (guanidinium ion) to a site that in the wild-type protein was occupied by the guanidino head group of an Arg. In the design template, a duplicated helix is flanked by two loop regions of different stabilities. In the "on" state, the N-terminal loop is weakly structured, whereas the C-terminal loop has a well defined conformation that is stabilized by means of nonbonded interactions with the Arg head group. The truncation of the Arg to Ala destabilizes this loop and switches the protein to the "off" state, in which the duplicated helix is translocated approximately 20 A. Guanidinium binding restores the key interactions, restabilizes the C-terminal loop, and restores the "on" state. Thus, the presence of an external ligand, which is unrelated to the catalytic activity of the enzyme, triggers the inserted helix to translate 20 A away from the binding site. The results illustrate a proposed mechanism for protein evolution in which sequence duplication followed by point mutation can lead to the establishment of new function.
The line below this paragraph, {{ABSTRACT_PUBMED_15286283}}, adds the Publication Abstract to the page
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{{ABSTRACT_PUBMED_15286283}}


==About this Structure==
==About this Structure==
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==Reference==
==Reference==
Use of sequence duplication to engineer a ligand-triggered, long-distance molecular switch in T4 lysozyme., Yousef MS, Baase WA, Matthews BW, Proc Natl Acad Sci U S A. 2004 Aug 10;101(32):11583-6. Epub 2004 Jul 30. PMID:[http://www.ncbi.nlm.nih.gov/pubmed/15286283 15286283]
Use of sequence duplication to engineer a ligand-triggered, long-distance molecular switch in T4 lysozyme., Yousef MS, Baase WA, Matthews BW, Proc Natl Acad Sci U S A. 2004 Aug 10;101(32):11583-6. Epub 2004 Jul 30. PMID:[http://www.ncbi.nlm.nih.gov/pubmed/15286283 15286283]
Structural characterization of an engineered tandem repeat contrasts the importance of context and sequence in protein folding., Sagermann M, Baase WA, Matthews BW, Proc Natl Acad Sci U S A. 1999 May 25;96(11):6078-83. PMID:[http://www.ncbi.nlm.nih.gov/pubmed/10339544 10339544]
Long-distance conformational changes in a protein engineered by modulated sequence duplication., Sagermann M, Gay L, Matthews BW, Proc Natl Acad Sci U S A. 2003 Aug 5;100(16):9191-5. Epub 2003 Jul 17. PMID:[http://www.ncbi.nlm.nih.gov/pubmed/12869697 12869697]
[[Category: Enterobacteria phage t4]]
[[Category: Enterobacteria phage t4]]
[[Category: Lysozyme]]
[[Category: Lysozyme]]
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[[Category: Protein engineering]]
[[Category: Protein engineering]]
[[Category: T4 lysozyme]]
[[Category: T4 lysozyme]]
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