DNA Binding Exerted by a Bacterial Gene Regulator with an Extensive Coiled-coil Domain (∗)

Although quite common in the eukaryotic cell, bacterial proteins with an extensive coiled-coil domain are still relatively rare. One of the few thus far documented examples, TlpA from Salmonella typhimurium, is characterized by a remarkably long (250 amino acids) α-helical coiled-coil domain. Herein...

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Bibliographic Details
Published in:The Journal of biological chemistry 1996-05, Vol.271 (21), p.12626-12631
Main Authors: Hurme, Reini, Berndt, Kurt D., Namork, Ellen, Rhen, Mikael
Format: Article
Language:English
Subjects:
Bacterial Proteins - chemistry
Bacterial Proteins - genetics
Bacterial Proteins - metabolism
Base Sequence
design
DNA - metabolism
DNA-Binding Proteins - genetics
DNA-Binding Proteins - metabolism
leucine zipper
Medicin och hälsovetenskap
Microscopy, Electron
Molecular Sequence Data
Mutation
Promoter Regions, Genetic
protein
Protein Binding
Protein Conformation
Salmonella typhimurium
Salmonella typhimurium - metabolism
transcription factors
Transcription, Genetic
virulence plasmid
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Summary:Although quite common in the eukaryotic cell, bacterial proteins with an extensive coiled-coil domain are still relatively rare. One of the few thus far documented examples, TlpA from Salmonella typhimurium, is characterized by a remarkably long (250 amino acids) α-helical coiled-coil domain. Herein, we demonstrate that TlpA is a novel, sequence-specific DNA-binding protein. Several tlpA deletion mutants have been constructed, and their corresponding protein products were purified and tested for DNA binding. Two of the mutant proteins were shown to be deficient in DNA binding. Both mutants were analyzed by circular dichroism and electron microscopy, supporting the notion that mutant proteins were largely intact despite lacking the amino acid residues necessary for DNA binding. In vivo studies with transcriptional tlpA-lacZ fusions demonstrated that TlpA acts as a repressor. Using the repressor phenotype as a readout, the chain exchange previously described in vitro could also be confirmed in vivo. We believe the coiled-coil domain acts not only as a dimerization interface but could also serve a role as a flexible modulator of the protein-DNA interaction.
ISSN:0021-9258
1083-351X
1083-351X
DOI:10.1074/jbc.271.21.12626