Identification and characterization of an outer membrane receptor gene in Acinetobacter baumannii required for utilization of desferricoprogen, rhodotorulic acid, and desferrioxamine B as xenosiderophores.
In this study, we found that Acinetobacter baumannii utilized exogenously supplied desferricoprogen, rhodotorulic acid, and desferrioxamine B for growth under iron-limiting conditions. The ferric uptake regulator (Fur) titration assay method was then successfully applied to select iron-regulated genes in A. baumannii genomic libraries. Part of the nucleotide sequence homologous to Escherichia coli, fhuE, obtained from one of the positive clones allowed us to clone the entire gene, which was named fhuE. The fhuE gene had an amino acid sequence consistent with the N-terminal amino acid sequence of the 76-kDa iron-repressible outer membrane proteins in A. baumannii. Reverse transcription-polymerase chain reaction analysis demonstrated that fhuE mRNA is transcribed under iron-limiting conditions, consistent with the presence of a sequence homologous to the consensus Fur box in the promoter region. Disruption of fhuE resulted in the loss of expression of the 76-kDa protein. In addition, the double disruptant of fhuE and basD, which encodes one of the biosynthetic genes for the cognate siderophore acinetobactin, was unable to grow in the presence of desferricoprogen, rhodotorulic acid or desferrioxamine B. However, growth of the double disruptant was restored by complementation with fhuE, demonstrating that A. baumannii FhuE functions as the receptor common to coprogen, ferric rhodotorulic acid and ferrioxamine B.
College of Pharmaceutical Sciences, Matsuyama University, Japan. tfunahas@cc.matsuyama-u.ac.jp
Tatsuya
T
Funahashi
Tomotaka
T
Tanabe
Kazutoshi
K
Mihara
Katsushiro
K
Miyamoto
Hiroshi
H
Tsujibo
Shigeo
S
Yamamoto
D040981:Acinetobacter baumannii / Q000235:genetics* / Q000378:metabolism / Q000472:pathogenicity; D000595:Amino Acid Sequence; D001425:Bacterial Outer Membrane Proteins / Q000235:genetics* / Q000378:metabolism; D001483:Base Sequence; D003001:Cloning, Molecular; D003676:Deferoxamine / Q000378:metabolism; D054659:Diketopiperazines / Q000378:metabolism; D004926:Escherichia coli / Q000235:genetics; D029968:Escherichia coli Proteins / Q000235:genetics* / Q000378:metabolism; D005798:Genes, Bacterial; D006877:Hydroxamic Acids / Q000378:metabolism; D007093:Imidazoles / Q000378:metabolism; D007501:Iron / Q000378:metabolism*; D008969:Molecular Sequence Data; D010080:Oxazoles / Q000378:metabolism; D010879:Piperazines / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D011956:Receptors, Cell Surface / Q000235:genetics* / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D017385:Sequence Homology; D017262:Siderophores / Q000378:metabolism*; D014158:Transcription, Genetic
D001425:Bacterial Outer Membrane Proteins; D054659:Diketopiperazines; D029968:Escherichia coli Proteins; C064531:FHUE protein, E coli; D006877:Hydroxamic Acids; D007093:Imidazoles; D010080:Oxazoles; D010879:Piperazines; D012333:RNA, Messenger; D011956:Receptors, Cell Surface; D017262:Siderophores; C091186:acinetobactin; C003305:rhodotorulic acid; D007501:Iron; D003676:Deferoxamine; C047664:desferricoprogen