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The DNA binding protein Tfx from Methanobacterium thermoautotrophicum : structure, DNA binding properties and transcriptional regulation
Author(s) -
Hochheimer Andreas,
Hedderich Reiner,
Thauer Rudolf K.
Publication year - 1999
Publication title -
molecular microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.857
H-Index - 247
eISSN - 1365-2958
pISSN - 0950-382X
DOI - 10.1046/j.1365-2958.1999.01204.x
Subject(s) - operon , biology , dna , hmg box , dna footprinting , dna binding domain , electrophoretic mobility shift assay , microbiology and biotechnology , binding domain , transcription (linguistics) , dna binding site , dna binding protein , binding site , biochemistry , promoter , transcription factor , escherichia coli , gene , gene expression , linguistics , philosophy
In Methanobacterium thermoautotrophicum , the fmdECB operon encoding the molybdenum formylmethanofuran dehydrogenase is directly preceded by an open reading frame tfx predicted to encode a DNA binding protein. The 16.1 kDa protein has an N‐terminal basic domain with a helix–turn–helix motif for DNA binding and a C‐terminal acidic domain possibly for transcriptional activation. We report here on the DNA binding properties of the Tfx protein heterologously overproduced in Escherichia coli . Tfx was found to bind specifically to a DNA sequence downstream of the promoter of the fmdECB operon, as shown by electrophoretic mobility shift assays and DNase I footprint analysis. Northern blot hybridizations revealed that transcription of tfx is repressed during the growth of M. thermoautotrophicum in the presence of tungstate. Based on its structure and properties, the DNA binding protein Tfx is proposed to be a transcriptional regulator composed of a basic DNA binding domain and an acidic activation domain.