title: Short peptides act as inducers, anti-inducers and corepressors of Tet repressor.
abstract: Protein allostery plays a pivotal role in many regulatory processes. Prominent examples are cell-surface receptors, which allosterically transmit ligand-generated signals to their cytoplasmic domains, or bacterial transcription factors, which alternate between a free conformation and a DNA-bound conformation in response to binding an effector molecule. The bacterial transcription factor Tet repressor (TetR) belongs to the latter category and is regarded as highly adapted to tetracyclines (tc's) as effectors. However, peptides isolated in this study were able to trigger distinct allosteric behavior including induction, anti-induction and corepression. Binding of the peptides' C-terminal residues consistently occurs within the tc-binding pocket of TetR. However, an extensive analysis of TetR mutants revealed that inducing and anti-inducing peptides utilize different parts of the binding pocket to elicit their respective regulatory responses. This study demonstrates that even for transcription factors evolved for high effector specificity, alternative molecular structures can exert similar and even novel effects, provided that sufficient chemical diversity and molecular flexibility, as found in peptide libraries, is accompanied by an efficient in vivo selection system. The high number of bioactive peptides and their extensive sequence diversity suggests that switching from small-molecule-controlled transcription regulation to a signal transduction network might be rather easily accomplished. These findings will strongly affect protein-mediated regulation of gene expression.
authors.affiliation: Lehrstuhl für Mikrobiologie, Department Biologie, Friedrich-Alexander-Universität Erlangen-Nürnberg, 91058 Erlangen, Germany.
authors.forename: Dagmar
authors.initials: D
authors.lastname: Goeke
authors.forename: Daniela
authors.initials: D
authors.lastname: Kaspar
authors.forename: Christoph
authors.initials: C
authors.lastname: Stoeckle
authors.forename: Sandra
authors.initials: S
authors.lastname: Grubmüller
authors.forename: Christian
authors.initials: C
authors.lastname: Berens
authors.forename: Marcus
authors.initials: M
authors.lastname: Klotzsche
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Hillen
mesh_terms: D000494:Allosteric Regulation; D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000737:chemistry / Q000378:metabolism; D001665:Binding Sites; D056970:Co-Repressor Proteins / Q000737:chemistry* / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000737:chemistry / Q000378:metabolism; D004926:Escherichia coli / Q000378:metabolism; D008969:Molecular Sequence Data; D019151:Peptide Library; D010455:Peptides / Q000737:chemistry* / Q000378:metabolism*; D011487:Protein Conformation; D012097:Repressor Proteins / Q000737:chemistry* / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins / Q000737:chemistry / Q000378:metabolism; D013754:Tetracyclines / Q000378:metabolism; D014157:Transcription Factors / Q000737:chemistry / Q000378:metabolism; D015003:Yeasts / Q000378:metabolism
chemical_list: D001426:Bacterial Proteins; D056970:Co-Repressor Proteins; D004268:DNA-Binding Proteins; D019151:Peptide Library; D010455:Peptides; D012097:Repressor Proteins; D029701:Saccharomyces cerevisiae Proteins; D013754:Tetracyclines; D014157:Transcription Factors; C034811:tetracycline resistance-encoding transposon repressor protein