The Thermus thermophilus comEA/comEC operon is associated with DNA binding and regulation of the DNA translocator and type IV pili.
Natural transformation systems and type IV pili are linked in many naturally competent bacteria. In the Gram-negative bacterium Thermus thermophilus, a leading model organism for studies of DNA transporters in thermophilic bacteria, seven competence proteins play a dual role in both systems, whereas two competence genes, comEA and comEC, are suggested to represent unique DNA translocator proteins. Here we show that the T. thermophilus ComEA protein binds dsDNA and is anchored in the inner membrane. comEA is co-transcribed with the flanking comEC gene, and transcription of this operon is upregulated by nutrient limitation and low temperature. To our surprise, a comEC mutant was impaired in piliation. We followed this observation and uncovered that the impaired piliation of the comEC mutant is due to a transcriptional downregulation of pilA4 and the pilN both playing a dual role in piliation and natural competence. Moreover, the comEC mutation resulted in a dramatic decrease in mRNA levels of the pseudopilin gene pilA1, which is unique for the DNA transporter. We conclude that ComEC modulates transcriptional regulation of type IV pili and DNA translocator components thereby mediating a response to extracellular parameters.
Molecular Microbiology and Bioenergetics, Institute of Molecular Biosciences, Goethe University Frankfurt, Frankfurt am Main, Germany.
Ralf
R
Salzer
Molecular Microbiology and Bioenergetics, Institute of Molecular Biosciences, Goethe University Frankfurt, Frankfurt am Main, Germany.
Timo
T
Kern
Department of Structural Biology, Max-Planck Institute of Biophysics, Frankfurt am Main, 60438, Germany.
Friederike
F
Joos
Molecular Microbiology and Bioenergetics, Institute of Molecular Biosciences, Goethe University Frankfurt, Frankfurt am Main, Germany.
Beate
B
Averhoff
D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D001693:Biological Transport, Active / Q000235:genetics*; D004247:DNA / Q000378:metabolism; D061269:DNA Transformation Competence / Q000235:genetics*; D004268:DNA-Binding Proteins / Q000235:genetics*; D010861:Fimbriae, Bacterial / Q000235:genetics* / Q000378:metabolism; D008565:Membrane Proteins / Q000235:genetics*; D009154:Mutation; D009876:Operon / Q000235:genetics; D016963:Thermus thermophilus / Q000235:genetics*; D014158:Transcription, Genetic / Q000235:genetics
D001426:Bacterial Proteins; D004268:DNA-Binding Proteins; D008565:Membrane Proteins; D004247:DNA