Identification of the As(III)/Sb(III) binding domain and the dimerization of the ArsR represser
Article
Xu, C, Shi, W, Rosen, BP. (1996). Identification of the As(III)/Sb(III) binding domain and the dimerization of the ArsR represser
. FASEB JOURNAL, 10(6),
Xu, C, Shi, W, Rosen, BP. (1996). Identification of the As(III)/Sb(III) binding domain and the dimerization of the ArsR represser
. FASEB JOURNAL, 10(6),
The homologous ArsR repressors encoded by the E. coli chromosomal and plasmid R773 arsR genes métallo regulate transcription of their respective ars opérons. From genetic and biochemical studies ArsR residues Cys32, Cys34 and Cys37 were identified as ligands to As(III) or Sb(lII). However, only Cys32 and Cys34 are required for transcriptional regulation, suggesting that, while all three cysteine thiolates are arsenic ligands, binding to only Cys32 and Cys34 produce the conformât! on al change that results in release of the repressor from the DNA. Purified chromosomal ArsR eluted from a gel filtration column as a homodimer. ArsR-ArsR interaction was observed using a yeast two-hybrid system. A series of ArsR deletions were tested using this system. It was found that deletion of amino acid residues 93 to the C-terminus (residue 117) had no effect on ArsR-ArsR interaction, while deletion of residues 61117 or residues 1-41 totally prevented interaction. When residues 89-117 were deleted, in vivo repression was reduced by 50%. This truncated ArsR eluted from a gel filtration column as a monomer. These results suggest that residues 89-93 may be important for dimerization of the ArsR repressor.
