Altered promoter recognition by mutant forms of the σ70 subunit of Escherichia coli RNA polymerase

A mutant spacer sequence between -35 and -10 elements makes the P lac promoter hyperactive and cAMP receptor protein-independent

“…The first kind of promoters (Ϫ35 promoters) is more common and characterized by the presence of the Ϫ10 element as well as a 6-bp (consensus sequence 5Ј-TTGACA-3Ј) in the Ϫ35 position (16). The Ϫ35 element also helps RNA polymerase binding through interaction with region 4.2 of 70 (2,5,17). It is believed that the spacer region between Ϫ35 and Ϫ10 (optimal length 17 bp) does not have any specific sequence requirement and simply facilitates the spatial alignment of the Ϫ10 and Ϫ35 elements in binding to the 2.4 and 4.2 regions of the factor (7,17,18).…”

The sapA promoter from Streptomyces coelicolor requires activation sites and initiator-like sequences but No -10 or -35 sequences

“…Temporally regulated transcription from the 18-bp sapA promoter does not fit well with current models of promoter recognition by most prokaryotic sigma factors that invoke key contacts to sequences around Ϫ35 and Ϫ10 bp upstream (11,27,34). Therefore, as in eukaryotic TATA-less promoters, it is possible that a protein binding at or near the transcription start site mediates formation of a transcription complex.…”

Crystallization and preliminary X-ray diffraction analysis of the mitochondrial transcription factor sc-mtTFB fromSaccharomyces cerevisiae

“…The co-factor sc-mtTFB, on the other hand, displays some similarities with bacterial '-factors such as '70 from Escherichia coli (Jang & Jaehning, 1991). In '70, these conserved regions have been suggested to function in promoter recognition and melting and in the stabilization of the E. coli RNAP (Helmann & Chamberlin, 1988;Siegele et al, 1989). A recent study showed that sc-mtTFB binds to sc-mtRNAP prior to DNA binding and is released from the core enzyme after transcription initiation (Mangus et al, 1994).…”