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Iron‐responsive gene expression in Pseudomonas fluorescens M114; cloning and characterization of a transcription‐activating factor, PbrA
Author(s) -
Sexton Ray,
Gill Paul R.,
Callanan Michael J.,
O'Sullivan Daniel J.,
Dowling David N.,
O'Gara Fergal
Publication year - 1995
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.1365-2958.1995.tb02244.x
Subject(s) - biology , open reading frame , mutant , gene , pseudomonas fluorescens , pseudomonas putida , sigma factor , transcription (linguistics) , promoter , microbiology and biotechnology , rpon , genetics , peptide sequence , gene expression , linguistics , philosophy , bacteria
Summary In response to iron limitation, Pseudomonas fluorescens M114 induces a number of genes including an iron‐scavenging siderophore termed pseudobactin M114, its cognate receptor, PbuA, and a casein protease. A Tn5 lacZ ‐induced mutant (M114FA1) was isolated that exhibits a pleiotropic phenotype and lacks the ability to express these iron‐regulated genes. A cosmid clone was identified which complements this mutation. This clone is capable of activating a number of iron‐regulated promoter fusion constructs from P. fluorescens M114 and Pseudomonas putida WCS358 and can also promote expression of these fusions in Escherichia coli. A series of insertion mutants was constructed by homologous recombination which were unable to transcribe the promoter fusions. DNA sequence analysis of the complementing region identified one open reading frame (ORF) termed pbrA ( p seucio b actin r egulation a ctivation) and the deduced amino acid sequence shows domains with significant homology to a number of ECF ( e xtra c ytoplasmic f unction) transcriptional regulators of the σ 70 sigma factor family, including fecl required for expression of the ferric dicitrate outer‐membrane receptor protein of E. coli. Sequences upstream of the pbrA gene suggest that transcription of pbrA may also be iron regulated.