Conformational changes of the Tet repressor induced by tetracycline trapping.

TitleConformational changes of the Tet repressor induced by tetracycline trapping.
Publication TypeJournal Article
Year of Publication1998
AuthorsOrth P, Cordes F, Schnappinger D, Hillen W, Saenger W, Hinrichs W
JournalJ Mol Biol
Date Published1998 Jun 05
KeywordsAmino Acid Sequence, Bacterial Proteins, Binding Sites, Crystallography, X-Ray, Escherichia coli, Gene Expression Regulation, Bacterial, Models, Molecular, Molecular Sequence Data, Mutation, Protein Conformation, Protein Structure, Secondary, Recombinant Fusion Proteins, Repressor Proteins, Tetracycline, Water

The X-ray crystal structure analysis of inducer-free Tet repressor, TetR, at 2.4 A resolution identifies one of two openings of the tunnel-like binding site as the entrance for the inducer tetracycline-Mg2+, [Mg Tc]+. Recognition and binding of the inducer unleashes conformational changes leading to the induced state of TetR. In the first step, the C-terminal turn of alpha-helix 6 unwinds, thereby altering the orientation of alpha-helix 4. This different orientation of alpha-helix 4 is stabilized by a series of hydrogen bonds mediated through a chain of eight water molecules. The alpha-helix 4 connects the DNA-binding domain (alpha-helices 1 to 3) to the rigid TetR core, and thus regulates gene expression through its respective orientations.

Alternate JournalJ Mol Biol
PubMed ID9642048

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