Premium
Structural origins for selectivity and specificity in an engineered bacterial repressor–inducer pair
Author(s) -
Klieber Michael A.,
Scholz Oliver,
Lochner Susanne,
Gmeiner Peter,
Hillen Wolfgang,
Muller Yves A.
Publication year - 2009
Publication title -
the febs journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.981
H-Index - 204
eISSN - 1742-4658
pISSN - 1742-464X
DOI - 10.1111/j.1742-4658.2009.07254.x
Subject(s) - tetr , repressor , inducer , tetracycline , mutant , ligand (biochemistry) , chemistry , hydrogen bond , gene , binding site , stereochemistry , gene expression , biophysics , biochemistry , biology , receptor , molecule , organic chemistry , antibiotics
The bacterial tetracycline transcription regulation system mediated by the tetracycline repressor (TetR) is widely used to study gene expression in prokaryotes and eukaryotes. To study multiple genes in parallel, a triple mutant TetR(K 64 L 135 I 138 ) has been engineered that is selectively induced by the synthetic tetracycline derivative 4‐de‐dimethylamino‐anhydrotetracycline (4‐ddma‐atc) and no longer by tetracycline, the inducer of wild‐type TetR. In the present study, we report the crystal structure of TetR(K 64 L 135 I 138 ) in the absence and in complex with 4‐ddma‐atc at resolutions of 2.1 Å. Analysis of the structures in light of the available binding data and previously reported TetR complexes allows for a dissection of the origins of selectivity and specificity. In all crystal structures solved to date, the ligand‐binding position, as well as the positioning of the residues lining the binding site, is extremely well conserved, irrespective of the chemical nature of the ligand. Selective recognition of 4‐ddma‐atc is achieved through fine‐tuned hydrogen‐bonding constraints introduced by the His64→Lys substitution, as well as a combination of hydrophobic effect and the removal of unfavorable electrostatic interactions through the introduction of Leu135 and Ile138.