1T8A

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

Summary for 1T8A

• Entry DOI: 10.2210/pdb1t8a/pdb
• Descriptor: Lysozyme, CHLORIDE ION, GUANIDINE, ... (5 entities in total)
• Functional Keywords: molecular switch, t4 lysozyme, nano-bitechnology, protein engineering, protein design, hydrolase
• Biological source: Enterobacteria phage T4
• Total number of polymer chains: 1
• Total formula weight: 19934.32

Authors

Yousef, M.S.,Baase, W.A.,Matthews, B.W. (deposition date: 2004-05-11, release date: 2004-08-17, Last modification date: 2024-02-14)

Primary citation

Yousef, M.S.,Baase, W.A.,Matthews, B.W.
Use of sequence duplication to engineer a ligand-triggered, long-distance molecular switch in T4 lysozyme.
Proc.Natl.Acad.Sci.USA, 101:11583-11586, 2004

PubMed Abstract: 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.

PubMed: 15286283
DOI: 10.1073/pnas.0404482101

Experimental method

X-RAY DIFFRACTION (2 Å)