title: Identification and characterization of a cluster of genes involved in biosynthesis and transport of acinetoferrin, a siderophore produced by Acinetobacter haemolyticus ATCC 17906T.
abstract: Acinetobacter haemolyticus ATCC 17906(T) is known to produce the siderophore acinetoferrin under iron-limiting conditions. Here, we show that an operon consisting of eight consecutive genes, named acbABCD and actBCAD, participates in the biosynthesis and transport of acinetoferrin, respectively. Transcription of the operon was found to be iron-regulated by a putative Fur box located in the promoter region of the first gene, acbA. Homology searches suggest that acbABCD and actA encode enzyme proteins involved in acinetoferrin biosynthesis and an outer-membrane receptor for ferric acinetoferrin, respectively. Mutants defective in acbA and actA were unable to produce acinetoferrin or to express the ferric acinetoferrin receptor under iron-limiting conditions. These abilities were rescued by complementation of the mutants with native acbA and actA genes. Secondary structure analysis predicted that the products of actC and actD may be inner-membrane proteins with 12 membrane-spanning helices that belong to the major facilitator superfamily proteins. ActC showed homology to Sinorhizobium meliloti RhtX, which has been characterized as an inner-membrane importer for ferric rhizobactin 1021 structurally similar to acinetoferrin. Compared to the parental ATCC 17906(T) strain, the actD mutant displayed about a 35 % reduction in secretion of acinetoferrin, which was restored by complementation with actD, suggesting that ActD acts as an exporter of the siderophore. Finally, the actB product was significantly similar to hypothetical proteins in certain bacteria, in which genes encoding ActBCA homologues are arranged in the same order as in A. haemolyticus ATCC 17906(T). However, the function of ActB remains to be clarified.
authors: Laboratory of Hygienic Chemistry, College of Pharmaceutical Sciences, Matsuyama University, 4-2 Bunkyo-cho, Matsuyama 790-8578, Japan.
authors: Tatsuya
authors: T
authors: Funahashi
authors: Laboratory of Hygienic Chemistry, College of Pharmaceutical Sciences, Matsuyama University, 4-2 Bunkyo-cho, Matsuyama 790-8578, Japan.
authors: Tomotaka
authors: T
authors: Tanabe
authors: Laboratory of Infectious Disease, College of Pharmaceutical Sciences, Matsuyama University, 4-2 Bunkyo-cho, Matsuyama 790-8578, Japan.
authors: Jun
authors: J
authors: Maki
authors: Department of Microbiology, Osaka University of Pharmaceutical Sciences, 4-20-1 Nasahara, Takatsuki, Osaka 569-1094, Japan.
authors: Katsushiro
authors: K
authors: Miyamoto
authors: Department of Microbiology, Osaka University of Pharmaceutical Sciences, 4-20-1 Nasahara, Takatsuki, Osaka 569-1094, Japan.
authors: Hiroshi
authors: H
authors: Tsujibo
authors: Laboratory of Hygienic Chemistry, College of Pharmaceutical Sciences, Matsuyama University, 4-2 Bunkyo-cho, Matsuyama 790-8578, Japan.
authors: Shigeo
authors: S
authors: Yamamoto
mesh_terms: D000150:Acinetobacter / Q000235:genetics / Q000378:metabolism*; D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D001483:Base Sequence; D001692:Biological Transport / Q000235:genetics; D002951:Citrates / Q000096:biosynthesis* / Q000737:chemistry / Q000378:metabolism*; D015964:Gene Expression Regulation, Bacterial; D005798:Genes, Bacterial; D006877:Hydroxamic Acids / Q000737:chemistry / Q000378:metabolism*; D007501:Iron / Q000378:metabolism; D008969:Molecular Sequence Data; D005810:Multigene Family; D009154:Mutation; D017422:Sequence Analysis, DNA; D017262:Siderophores / Q000096:biosynthesis / Q000378:metabolism
chemical_list: D001426:Bacterial Proteins; D002951:Citrates; D006877:Hydroxamic Acids; D017262:Siderophores; C086668:acinetoferrin; D007501:Iron