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Structural basis of transcriptional activation by the Mycobacterium tuberculosis intrinsic antibiotic-resistance transcription factor WhiB7.

ABSTRACT: In pathogenic mycobacteria, transcriptional responses to antibiotics result in induced antibiotic resistance. WhiB7 belongs to the Actinobacteria-specific family of Fe-S-containing transcription factors and plays a crucial role in inducible antibiotic resistance in mycobacteria. Here, we present cryoelectron microscopy structures of Mycobacterium tuberculosis transcriptional regulatory complexes comprising RNA polymerase σ^A-holoenzyme, global regulators CarD and RbpA, and WhiB7, bound to a WhiB7-regulated promoter. The structures reveal how WhiB7 interacts with σ^A-holoenzyme while simultaneously interacting with an AT-rich sequence element via its AT-hook. Evidently, AT-hooks, rare elements in bacteria yet prevalent in eukaryotes, bind to target AT-rich DNA sequences similarly to the nuclear chromosome binding proteins. Unexpectedly, a subset of particles contained a WhiB7-stabilized closed promoter complex, revealing this intermediate's structure, and we apply kinetic modeling and biochemical assays to rationalize how WhiB7 activates transcription. Altogether, our work presents a comprehensive view of how WhiB7 serves to activate gene expression leading to antibiotic resistance.

SUBMITTER: Lilic M

PROVIDER: S-EPMC8311663 | biostudies-literature |

REPOSITORIES: biostudies-literature

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