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#prokaryotic promoter

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Transcription in Prokaryotes

Consensus sequence of the -35 element is

Promoter anatomy reveals two conserved hexamers spaced seventeen base pairs apart. Upstream hexamer centered around -35 position consensus sequence TTGACA contacted by sigma70 region 4 helix-turn-helix domain. Downstream Pribnow box at -10 consensus TATAAT recognized by region 2. Spacer length crucial for simultaneous contact of both elements due to helical phasing. TTGACA sequence unambiguously defines -35 element, distinguishing it from -10, UP element recognized by α-CTD, or GC-rich eukaryotic SP1 site GGGCGG. Promoter strength correlates with closeness to TTGACA consensus for -35 interaction optimizing closed complex formation.

Ref: Alberts Chapter 6: -35 consensus TTGACA bacterial promoters; Watson Molecular Biology Gene Promoter table -35 element sequence

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Transcription in Prokaryotes

The -10 promoter element in E. coli is also called

Bacterial promoters contain 6-base AT-rich element centered near -10 relative to transcription start site, originally described by Pribnow examining phage T7 and E. coli promoters. Sequence TATAAT facilitates duplex melting due to low stability and is specifically recognized by sigma70 region 2 for open complex formation. Eukaryotic TATA box termed Hogness box located -30 recognized by TBP, distinct in position and factor. -35 element consensus TTGACA, UP element AT-rich upstream, none termed Pribnow. Therefore -10 promoter element specifically designated Pribnow box in prokaryotic literature referencing initiator melting element.

Ref: Berg Biochemistry Section 28.2: -10 element Pribnow box nomenclature; Pribnow 1975 PNAS TATAAT sequence; Watson Chapter 13 Promoter elements naming

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