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The carR region encodes a light-inducible promoter, a negative regulator of the promoter and a trans-acting activator that controls the light-inducible Myxococcus xanthus carotenoid biosynthesis regulon. DNA sequence analysis revealed, downstream of the promoter, three translationally coupled genes, carQ, carR and carS. Sequencing of mutations demonstrated that carR encoded the negative regulator and was an integral membrane protein. Mutant construction and sequencing revealed that carS was the trans-acting activator and that carQ was a positive regulator of the promoter. Neither gene encodes proteins with known sequence-specific DNA-binding motifs. The sequence of the light-inducible promoter region, identified by primer extension analysis, showed similarity to the consensus sequence of the Escherichia coli stress response ('heat-shock') promoters.

Original publication




Journal article


Mol Microbiol

Publication Date





713 - 735


Amino Acid Sequence, Base Sequence, Carotenoids, Cloning, Molecular, Consensus Sequence, DNA Primers, DNA, Bacterial, Escherichia coli, Genes, Bacterial, Genes, Regulator, Light, Models, Genetic, Molecular Sequence Data, Mutation, Myxococcus xanthus, Open Reading Frames, Promoter Regions, Genetic, Restriction Mapping, Sequence Homology, Nucleic Acid, Trans-Activators