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#-10 promoter

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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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Transcription in Prokaryotes

Which subunit recognizes the -10 and -35 promoter elements?

Within bacterial holoenzyme, sequence-specific readout of promoter consensus relies predominantly on sigma factor rather than core catalytic subunits. Sigma70 region 4.2 presents helix-turn-helix motif inserting into major groove at -35 element TTGACA, while region 2.4 interacts with -10 Pribnow box TATAAT and captures flipped bases to drive melting. α subunit C-terminal domain may touch UP element AT-rich tract, but -10 and -35 recognition is sigma intrinsic. β and β' subunits shape downstream DNA channel and catalytic Mg2+ but do not determine promoter consensus identity. Exchange of sigma alters promoter preference accordingly.

Ref: Alberts Molecular Biology Cell Chapter 6: Sigma subunit recognizes -10 -35 elements; Watson Chapter 13 Sigma-DNA contacts

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