title: Promoter recognition by bacterial alternative sigma factors: the price of high selectivity?
abstract: A key step in bacterial transcription initiation is melting of the double-stranded promoter DNA by the RNA polymerase holoenzyme. Primary sigma factors mediate the melting of thousands of promoters through a conserved set of aromatic amino acids. Alternative sigmas, which direct transcription of restricted regulons, lack the full set of melting residues. In this issue of Genes & Development, Koo and colleagues (pp. 2426-2436) show that introducing the primary sigma melting residues into alternative sigmas relaxes their promoter specificity, pointing to a trade-off of reduced promoter melting capacity for increased promoter stringency.
authors.affiliation: The Rockefeller University, New York, New York 10065, USA.
authors.forename: Andrey
authors.initials: A
authors.lastname: Feklistov
authors.forename: Seth A
authors.initials: SA
authors.lastname: Darst
mesh_terms: D001419:Bacteria / Q000378:metabolism*; D001426:Bacterial Proteins / Q000378:metabolism*; D009691:Nucleic Acid Denaturation; D011401:Promoter Regions, Genetic; D012808:Sigma Factor / Q000378:metabolism*
chemical_list: D001426:Bacterial Proteins; D012808:Sigma Factor