8dh0
T7 RNA polymerase elongation complex with unnatural base dDs
Structural highlights
FunctionRPOL_BPT7 DNA-dependent RNA polymerase catalyzes the transcription of DNA into RNA using the four ribonucleoside triphosphates as substrates. Responsible for the transcription of the late genes of T7. It is rifampicin-resistant. It recognizes a specific promoter sequence, unwinds the double-stranded RNA to expose the coding strand for templating, initiates transcription preferentially with a purine. Publication Abstract from PubMedBacteriophage T7 RNA polymerase (T7 RNAP) is widely used for synthesizing RNA molecules with synthetic modifications and unnatural base pairs (UBPs) for a variety of biotechnical and therapeutic applications. However, the molecular basis of transcription recognition of UBPs by T7 RNAP remains poorly understood. Here we focused on a representative UBP, 7-(2-thienyl)-imidazo[4,5-b]pyridine (Ds) and pyrrole 2-carbaldehyde (Pa), and investigated how the hydrophobic Ds-Pa pair is recognized by T7 RNAP. Our kinetic assays revealed that T7 RNAP selectively recognizes the Ds or Pa base in the templates and preferentially incorporates their cognate unnatural base nucleotide substrate (PaTP or DsTP) over natural NTPs. Our structural studies reveal that T7 RNAP recognizes the unnatural substrates at the pre-insertion state in a distinct manner compared to natural substrates. These results provide mechanistic insights into transcription recognition of UBP by T7 RNAP and provide valuable information for designing the next generation of UBPs. Structural basis of transcription recognition of a hydrophobic unnatural base pair by T7 RNA polymerase.,Oh J, Kimoto M, Xu H, Chong J, Hirao I, Wang D Nat Commun. 2023 Jan 13;14(1):195. doi: 10.1038/s41467-022-35755-8. PMID:36635281[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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