Open AccessThe −24/−12 promoter comes of age
Author(s) -
Thöny Beat,
Hennecke Hauke
Publication year - 1989
Publication title -
fems microbiology letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.899
H-Index - 151
eISSN - 1574-6968
pISSN - 0378-1097
DOI - 10.1111/j.1574-6968.1989.tb03404.x
Subject(s) - promoter , sigma factor , biology , gene , rpon , enhancer , consensus sequence , genetics , rna polymerase , regulatory sequence , gene expression , transcription (linguistics) , regulation of gene expression , transcription factor , microbiology and biotechnology , rna , peptide sequence , linguistics , philosophy
A new bacterial promoter type has been identified in the last few years. Originally designated as nif (= ni trogen f ixation) or ntr (= n i t rogen r egulation) consensus promoter, it is now evident that this promoter occurs in many different bacterial species and is used not only for genes involved in nitrogen assimilation but also for genes determinating many other unrelated metabolic functions. The general features of this type of promoter are (i) the conserved −24(GG)/−12(GC) consensus sequence, (ii) its recognition by a specific RNA polymerase sigma factor, σ 54 , which is encoded by the ntrA gene (synonyms: glnF , rpoN , rpoE ), and (iii) the requirement for a transcriptional regulatory protein to activate the expression of the associated genes. In addition, many (but not all) of these genes possess a promoter‐upstream activator sequence (enhancer) which is the target site for the binding of the activating protein and is required for maximal expression. In some cases, in which gene expression does not appear to be dependent on the presence of upstream binding sites, the activating protein may interact directly with the RNA polymerase‐promoter complex. In conclusion, the expression from all −24/−12 consensus promoters known to date is positively controlled.