What is the proofreading mechanism of RNAP for base-by-base repair?

Phosphorolytic editing is a mechanism utilized by RNA polymerase (RNAP) that plays a crucial role in the fidelity of RNA synthesis. This process involves the ability of RNAP to recognize and correct errors made during the transcription of RNA by incorporating pyrophosphate (PPi) to cleave the erroneous nucleotide, effectively removing the misincorporated base. The action of phosphorolytic editing allows RNAP to backtrack by a few nucleotides in the RNA strand, leading to the hydrolysis of the incorrect RNA while preserving the integrity of the template DNA.

This mechanism ensures that the transcription process is both efficient and accurate, as it allows the polymerase to rectify mistakes without completely dissociating from the DNA template. The importance of this proofreading capability is underscored by the fact that the accuracy of the transcribed RNA is critical for proper gene expression and downstream processes.

Other mechanisms, such as exonucleolytic editing, involve the trimming of nucleotides from the ends of the RNA molecule, which does not correspond directly to the base-by-base correction happening during transcription. Hydrolytic editing similarly refers to different processes that are not specific to the action of RNAP during transcription. Transcriptional proofreading is a broader term that