Which promoter elements are typical of bacterial transcription initiation?

Which promoter elements are typical of bacterial transcription initiation?

• A. The -35 and -10 sequences recognized by the sigma factor (the Pribnow box is at -10)
• B. TATA box and CAAT box
• C. -80 and -40
• D. Start codon and Shine-Dalgarno

Answer: (A)

Bacterial transcription initiation centers on RNA polymerase recognizing promoter sequences through its sigma factor. The essential promoter elements are the -35 region and the -10 region upstream of the transcription start site, with the -10 region containing the Pribnow box. The sigma factor binds these sequences to position the polymerase and help unwind the DNA so transcription can begin at +1; the typical spacing between these elements and the start site is about 17 base pairs, which is important for proper interaction. Other options reflect promoter features from different systems or processes. A TATA box and CAAT box are characteristic of many eukaryotic promoters, the -80 and -40 aren’t standard bacterial promoter landmarks, and the start codon together with the Shine-Dalgarno sequence relate to translation initiation rather than transcription initiation.

Bacterial transcription initiation centers on RNA polymerase recognizing promoter sequences through its sigma factor. The essential promoter elements are the -35 region and the -10 region upstream of the transcription start site, with the -10 region containing the Pribnow box. The sigma factor binds these sequences to position the polymerase and help unwind the DNA so transcription can begin at +1; the typical spacing between these elements and the start site is about 17 base pairs, which is important for proper interaction.

Other options reflect promoter features from different systems or processes. A TATA box and CAAT box are characteristic of many eukaryotic promoters, the -80 and -40 aren’t standard bacterial promoter landmarks, and the start codon together with the Shine-Dalgarno sequence relate to translation initiation rather than transcription initiation.