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Mutations in genes downstream of the rpoN gene (encoding σ 54 ) of Klebsiella pneumoniae affect expression from σ 54 ‐dependent promoters
Author(s) -
Merrick M. J.,
Coppard J. R.
Publication year - 1989
Publication title -
molecular microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.857
H-Index - 247
eISSN - 1365-2958
pISSN - 0950-382X
DOI - 10.1111/j.1365-2958.1989.tb00162.x
Subject(s) - biology , rpon , gene , promoter , klebsiella pneumoniae , genetics , microbiology and biotechnology , gene expression , escherichia coli
Summary Two open reading frames (ORFs), designated ORF95 and ORF162, downstream of the Klebsiella pneumoniae σ 54 structural gene (rpoN) have been sequenced and shown to encode polypeptides of 12kD and 16kD, respectively. ORFs homologous to ORF95 are present downstream of four out of five rpoN genes sequenced to date from a range of Gram‐negative bacteria, and ORF162 is also conserved, at least in Pseudomonas putida. Chromosomal mutations have been created in each gene using a kan cassette and both have the same phenotype, i.e. they cause an increase in the level of expression from σ 54 ‐dependent promoters. We propose that the products of both genes function to modulate the activity of Eσ 54 , although a physiological role for these proteins has not yet been identified.