- SP6 RNA polymerase is a DNA-dependent RNA polymerase derived from Salmonella bacteriophage SP6, commonly used for in vitro transcription of RNA.
- Like T7 and T3 RNA polymerases, SP6 recognizes a highly specific promoter sequence—called the SP6 promoter—and initiates transcription immediately downstream.
- It produces RNA transcripts with high fidelity and efficiency but, importantly, only from templates containing its cognate SP6 promoter. This enzyme functions optimally in defined buffer conditions and does not require additional transcription factors, making it ideal for controlled, cell-free RNA synthesis.
- SP6 RNA polymerase is widely used in molecular biology for generating RNA probes for Northern blotting or in situ hybridization, mRNA transcripts for microinjection into oocytes or embryos, and RNA templates for in vitro translation systems.
- It is particularly favored in experiments involving eukaryotic mRNA synthesis, such as in Xenopus systems, where capped and polyadenylated RNA is injected to study gene function.
- To ensure precise transcription, researchers often use linearized plasmid templates ending at defined restriction sites beyond the gene of interest.
- SP6 is also valuable in applications requiring orthogonal control over transcription—since its specificity prevents cross-reactivity with T7 or T3 systems, multiple RNA species can be transcribed from a single template under different promoters.
- Altogether, SP6 RNA polymerase is a specialized yet essential tool for generating high-quality RNA for structural, functional, and developmental biology studies.
