fhuAof Actinobacillus pleuropneumoniaeEncodes a Ferrichrome Receptor but Is Not Regulated by Iron

ABSTRACTThe swine pathogen Actinobacillus pleuropneumoniaepossesses a 75-kDa outer membrane protein (OMP), FhuA, the receptor for ferrichrome, a hydroxamate-type siderophore. Polyclonal serum to FhuA reacted with OMP preparations from 12 serotypes of A. pleuropneumoniaeunder conditions of iron repletion and restriction. Reverse transcription-PCR confirmed that A. pleuropneumoniae fhuAexpression is not upregulated in response to low iron levels. An A. pleuropneumoniae fhuAdeletion mutant was generated and showed abolishment of ferrichrome uptake.