PMID: 15689399 , Related PDB id: 1U9P
Authors:
Tabtiang RK, Cezairliyan BO, Grant RA, Cochrane JC, Sauer RT
Title:
Consolidating critical binding determinants by noncyclic rearrangement of protein secondary structure.
Journal:
Proc Natl Acad Sci U S A. 2005 Feb 15;102(7):2305-9. Epub 2005 Feb 2.
Abstract:
We designed a single-chain variant of the Arc repressor homodimer in which the beta strands that contact operator DNA are connected by a hairpin turn and the alpha helices that form the tetrahelical scaffold of the dimer are attached by a short linker. The designed protein represents a noncyclic permutation of secondary structural elements in another single-chain Arc molecule (Arc-L1-Arc), in which the two subunits are fused by a single linker. The permuted protein binds operator DNA with nanomolar affinity, refolds on the sub-millisecond time scale, and is as stable as Arc-L1-Arc. The crystal structure of the permuted protein reveals an essentially wild-type fold, demonstrating that crucial folding information is not encoded in the wild-type order of secondary structure. Noncyclic rearrangement of secondary structure may allow grouping of critical active-site residues in other proteins and could be a useful tool for protein design and minimization.