Membrane insertion of the bacterial signal transduction protein ToxR and requirements of transcription activation studied by modular replacement of different protein substructures.
The Vibrio cholerae protein ToxR is an integral membrane protein that acts as a transcription activator in response to environmental signals; it controls expression of toxin genes ctxA and ctxB, along with a variety of other genes related to pathogenicity. Here it is shown that: (i) ToxR has a modular architecture and that activation of transcription starting at the ctx promoter depends strictly on dimerization of the periplasmic ToxR domain; (ii) the transmembrane (TM) region of ToxR is sufficient as a topogenic signal but not for stable membrane anchoring of the protein; (iii) the TM region has no special function in signal transduction and (iv) a proline residue located within the TM region minimizes background transcription activation, most plausibly by reducing TM-TM interaction. Possible applications of ToxR as a technical tool for analysing protein-protein interactions between pairs of arbitrary TM domains are discussed.
Kolmar
H
H
Institut für Molekulare Genetik, George-August-Universität Göttingen, Germany.
Hennecke
F
F
Götze
K
K
Janzer
B
B
Vogt
B
B
Mayer
F
F
Fritz
H J
HJ
D018528:ATP-Binding Cassette Transporters; D000595:Amino Acid Sequence; D001426:Bacterial Proteins; D001483:Base Sequence; D002352:Carrier Proteins / Q000235:genetics; D002772:Cholera Toxin / Q000235:genetics; D004268:DNA-Binding Proteins / Q000737:chemistry* / Q000235:genetics; D004926:Escherichia coli / Q000235:genetics; D029968:Escherichia coli Proteins; D005656:Fungal Proteins / Q000235:genetics; D005798:Genes, Bacterial / Q000235:genetics; D058619:Maltose-Binding Proteins; D008565:Membrane Proteins / Q000737:chemistry* / Q000235:genetics; D008969:Molecular Sequence Data; D009004:Monosaccharide Transport Proteins; D033902:Periplasmic Binding Proteins; D011392:Proline / Q000502:physiology; D011401:Promoter Regions, Genetic / Q000235:genetics; D011487:Protein Conformation; D011494:Protein Kinases / Q000235:genetics; D011993:Recombinant Fusion Proteins / Q000502:physiology; D029701:Saccharomyces cerevisiae Proteins; D015398:Signal Transduction / Q000502:physiology*; D014157:Transcription Factors / Q000737:chemistry* / Q000235:genetics; D015533:Transcriptional Activation / Q000502:physiology*; D014734:Vibrio cholerae / Q000235:genetics*
D018528:ATP-Binding Cassette Transporters; D001426:Bacterial Proteins; D002352:Carrier Proteins; D004268:DNA-Binding Proteins; D029968:Escherichia coli Proteins; D005656:Fungal Proteins; C461619:MalE protein, E coli; D058619:Maltose-Binding Proteins; D008565:Membrane Proteins; D009004:Monosaccharide Transport Proteins; D033902:Periplasmic Binding Proteins; D011993:Recombinant Fusion Proteins; D029701:Saccharomyces cerevisiae Proteins; D014157:Transcription Factors; C461599:maltose transport system, E coli; C499324:toxR protein, Vibrio cholerae; C066719:toxR protein, bacteria; D002772:Cholera Toxin; D011392:Proline; D011494:Protein Kinases