- The SP6 promoter is a short, well-characterized DNA sequence recognized specifically by SP6 RNA polymerase, derived from Salmonella bacteriophage SP6.
- Its consensus sequence is typically 5′-ATTTAGGTGACACTATAG-3′, and it must be positioned directly upstream of the DNA sequence to be transcribed.
- This promoter enables efficient and accurate initiation of in vitro transcription, making it a valuable tool in molecular biology for producing high-quality RNA.
- Like the T7 and T3 promoters, the SP6 promoter does not require additional transcription factors or cofactors, allowing it to function in simple, defined cell-free systems.
- The SP6 promoter is especially useful for generating RNA probes for in situ hybridization, mRNA for microinjection into embryos (e.g., Xenopus laevis), and for producing custom RNA transcripts for structural and functional studies.
- It is often included in cloning vectors along with T7 and T3 promoters to provide strand-specific or flexible transcription options.
- Because each of these phage promoters is recognized only by its corresponding RNA polymerase, the SP6 promoter allows orthogonal control of gene transcription, reducing cross-reactivity and improving experimental precision.
- While it may not be used as frequently as T7, the SP6 promoter remains an essential component of in vitro transcription workflows where its unique specificity and reliability are advantageous.
