Author(s):
Sá-Nogueira, Isabel de 
; Franco, Irina Saraiva ; Mota, Luís Jaime ; Soares, Cláudio Manuel
Date: 2006
Persistent ID: http://hdl.handle.net/10362/4205
Origin: Repositório Institucional da UNL
Document details
Functional domains of Bacillus subtilis transcription factor AraR and identific...
Description
Journal of Bacteriology (Apr 2006) 3024-3036 The Bacillus subtilis AraR transcription factor represses at least 13 genes required for the extracellular degradation of arabinose-containing polysaccharides, transport of arabinose, arabinose oligomers, xylose, and galactose, intracellular degradation of arabinose oligomers, and further catabolism of this sugar. AraR exhibits a chimeric organization comprising a small N-terminal DNA-binding domain that contains a winged helix-turn-helix motif similar to that seen with the GntR family and a larger C-terminal domain homologous to that of the LacI/GalR family. Here, a model for AraR was derived based on the known crystal structures of the FadR and PurR regulators from Escherichia coli. We have used random mutagenesis, deletion, and construction of chimeric LexA-AraR fusion proteins to map the functional domains of AraR required for DNA binding, dimerization, and effector binding. Moreover, predictions for the functional role of specific residues were tested by site-directed mutagenesis. In vivo analysis identified particular amino acids required for dimer assembly, formation of the nucleoprotein complex, and composition of the sugar-binding cleft. This work presents a structural framework for the function of AraR and provides insight into the mechanistic mode of action of this modular repressor.
Journal of Bacteriology (Apr 2006) 3024-3036 The Bacillus subtilis AraR transcription factor represses at least 13 genes required for the extracellular degradation of arabinose-containing polysaccharides, transport of arabinose, arabinose oligomers, xylose, and galactose, intracellular degradation of arabinose oligomers, and further catabolism of this sugar. AraR exhibits a chimeric organization comprising a small N-terminal DNA-binding domain that contains a winged helix-turn-helix motif similar to that seen with the GntR family and a larger C-terminal domain homologous to that of the LacI/GalR family. Here, a model for AraR was derived based on the known crystal structures of the FadR and PurR regulators from Escherichia coli. We have used random mutagenesis, deletion, and construction of chimeric LexA-AraR fusion proteins to map the functional domains of AraR required for DNA binding, dimerization, and effector binding. Moreover, predictions for the functional role of specific residues were tested by site-directed mutagenesis. In vivo analysis identified particular amino acids required for dimer assembly, formation of the nucleoprotein complex, and composition of the sugar-binding cleft. This work presents a structural framework for the function of AraR and provides insight into the mechanistic mode of action of this modular repressor.
Document Type
Article
Language English
Language English
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