What is the ideal spacing between the -10 and -35 regions of a prokaryotic promoter?

The ideal spacing between the -10 and -35 regions of a prokaryotic promoter is typically around 17 base pairs. This optimal distance allows the RNA polymerase to effectively recognize and bind to the promoter region for transcription initiation. The -10 region, also known as the Pribnow box, and the -35 region are crucial for the formation of the transcription initiation complex.

Having the regions spaced at about 17 base pairs facilitates proper alignment of the RNA polymerase with the DNA, which is essential for transcription to start efficiently. Deviations from this spacing can lead to reduced transcription efficiency, as the alignment might be suboptimal, impacting the binding of RNA polymerase. This well-characterized spacing is an important aspect of prokaryotic gene regulation and expression.