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The cyanobacterial principal σ factor region 1.1 is involved in DNA‐binding in the free form and in transcription activity as holoenzyme
Author(s) -
Imashimizu Masahiko,
Hanaoka Mitsumasa,
Seki Asako,
Murakami Katsuhiko S.,
Tanaka Kan
Publication year - 2006
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/j.febslet.2006.05.017
Subject(s) - rna polymerase , transcription (linguistics) , dna , polymerase , biology , transcription factor , promoter , microbiology and biotechnology , rna polymerase ii , rna , biochemistry , chemistry , gene , gene expression , linguistics , philosophy
Cyanobacterial principal σ factor, σ A , includes a specifically conserved cluster of basic amino acids in the amino‐terminal extension called region 1.1. We found that the σ A in a thermophilic cyanobacterium Thermosynechococcus elongatus BP‐1 binds DNA in the absence of the core RNA polymerase and that σ A lacking region 1.1 is not able to bind DNA. This indicates that, in the cyanobacterium, region 1.1 participates in DNA‐binding, rather than inhibiting the interaction between free σ and DNA, as found in other principal σ factors of eubacteria. The results of in vitro transcription assays with the reconstituted RNA polymerase showed that region 1.1 reduces transcription activity from the cpc promoter.