The iron-controlled fepA and fes-entF transcripts from the Escherichia coli enterobactin gene complex are expressed divergently from a limited genetic region, thereby suggesting the existence of a single, possibly overlapping promoter junction for these genes. The nucleotide sequence of a 1,997-base pair HpaI fragment specific for this genetic region allowed for the identification of an 1,122-base pair open reading frame as the previously uncharacterized fes gene. Its product, Fes (~ M(r) 42,573) plays an essential but as yet ambiguous role in the release of ferric iron from the ligand. An additional small open reading frame of 216 nucleotides (encoding a potential product of calculated M(r) 8,271) was also identified between fes and entF. A portion of the remaining nucleotide sequence defined a 320-base pair control region for both the fepA and fes-entF messages. Primer extension analyses placed the major in vivo transcription initiation sites to within 18 nucleotides of one another, thereby revealing a novel, extensively overlapping bidirectional promoter as well as long dual leader transcripts. This promoter region contains multiple overlapping nucleotide stretches which show strong homology to the consensus Fur repressor-binding sequence, forms of which are found in all E. coli iron-regulated promoters characterized to date.
|Original language||English (US)|
|Number of pages||7|
|Journal||Journal of Biological Chemistry|
|State||Published - 1988|