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Characterization of Mycobacterium tuberculosis LexA: recognition of a Cheo (Bacillus-type SOS) box
Farahnaz Movahedzadeh1, M Joseph Colston1, Elaine O Davis1
1Division of Mycobacterial Research, National Institute for Medical Research, Mill Hill, London NW7 1AA, UK.
Abstract:
The gene coding for the Mycobacterium tuberculosis homologue of LexA has been cloned and sequenced. Amino acids required for autocatalytic cleavage are conserved, whereas those important for specific DNA binding are not, when compared with Escherichia coli LexA. The transcriptional start site was mapped and a DNA sequence motif was identified which resembled the consensus Cheo box sequence involved in the regulation of DNA-damage-inducible genes in Bacillus subtilis. The M. tuberculosis-LexA protein was overexpressed in E. coli and purified by means of a His tag. The purified LexA was shown to bind to the Cheo box sequence found upstream of its own gene.