J. Membrillohernandez et al., ROLES OF RPOS (SIGMA(S)), IHF AND PPGPP IN THE EXPRESSION OF THE HMP GENE ENCODING THE FLAVOHEMOGLOBIN (HMP) OF ESCHERICHIA-COLI K-12, MGG. Molecular & general genetics, 254(5), 1997, pp. 599-603
The Escherichia coli K-12 gene hmp encodes the flavohemoglobin Hmp. A
hmp promoter Phi(hmp-lacZ)-operon fusion was constructed in the chromo
some and its activity measured during the growth cycle. Logarithmicall
y growing cultures had low levels of Phi(hmp-lacZ) expression, which i
ncreased two-fold at the onset of stationary phase in rich medium. The
effect was abolished in a strain carrying a null allele of the gene r
poS encoding the stationary phase-specific sigma subunit of RNA polyme
rase sigma(S). A himA mutation resulted in a 1.5-fold increase in expr
ession of Phi(hmp-lacZ), but did not affect growth phase-dependent reg
ulation. A single transcriptional start site was found for hmp, locate
d 38 bp upstream of the initiation codon. Putative Fnr boxes at positi
ons -2 to +11 occur in the hmp promoter region.