Open AccessBidirectional promoter in the hut(P) region of the histidine utilization (hut) operons from Klebsiella aerogenes
Author(s) -
A. J. Nieuwkoop,
Sandra L. Baldauf,
Michael E. S. Hudspeth,
R. Bender
Publication year - 1988
Publication title -
journal of bacteriology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.652
H-Index - 246
eISSN - 1067-8832
pISSN - 0021-9193
DOI - 10.1128/jb.170.5.2240-2246.1988
Subject(s) - biology , operon , rna polymerase , promoter , consensus sequence , binding site , microbiology and biotechnology , transcription (linguistics) , start codon , enterobacter aerogenes , nucleic acid sequence , gene , genetics , rna , gene expression , escherichia coli , messenger rna , peptide sequence , linguistics , philosophy
The hut(P) region (i.e., the region responsible for regulation of hutUH expression) of the Klebsiella aerogenes histidine utilization (hut) operons contains a bidirectional promoter. One transcript from this promoter encodes the hutUH operon; the role of the oppositely directed transcript is unknown, although it appears to be involved in regulating hutUH expression (A.J. Nieuwkoop, S.A. Boylan, and R.A. Bender, J. Bacteriol. 159:934-939, 1984). A 247-base-pair (bp) fragment containing hut(P) carries two RNA-polymerase-binding sites agree with the start sites of the two transcripts produced from hut(P) DNA in vitro and in vivo. The binding sites share a 4-bp region, suggesting that occupancy of the regulatory site precludes occupancy of the hutUH promoter, and vice versa. In the absence of positive effectors, the binding to the site responsible for hutUH transcription is weaker than the binding to the site responsible for regulation. The nucleotide sequence of the 250-bp fragment containing hut(P) contains two possible matches to the consensus sequence for Escherichia coli promoters, a better and worse match, corresponding in position to the stronger and weaker RNA-polymerase-binding sites, respectively. The sequence also contains a region similar to the consensus sequence for binding of the catabolite gene activator protein of E. coli. A sequence similar to the consensus for Ntr-dependent promoters was also found, overlapping both RNA-polymerase-binding sites, but it is not a functional promoter. Finally, an initiation codon preceded by a Shine-Dalgarno consensus sequence and followed by an open reading frame identifies a probable start of the hutU gene coding sequences.