Aptamers to the sigma factor mimic promoter recognition and inhibit transcription initiation by bacterial RNA polymerase

Site-specific aptamer inhibitors of Thermus RNA polymerase

Bacterial RNA polymerase (RNAP) is an RNA-synthesizing molecular machine and a target for antibiotics. In transcription, RNAP can interact with DNA sequence-specifically, during promoter recognition by the σ-containing holoenzyme, or nonspecifically, during productive RNA elongation by the core RNAP. We describe high-affinity single-stranded DNA aptamers that are specifically recognized by the core RNAP from Thermus aquaticus. The aptamers interact with distinct epitopes inside the RNAP main channel, including the rifamycin pocket, and sense the binding of other RNAP ligands such as rifamycin and the σ^A subunit. The aptamers inhibit RNAP activity and can thus be used for functional studies of transcription and development of novel RNAP inhibitors.