The siderophore-mediated iron acquisition systems of Acinetobacter baumannii ATCC 19606 and Vibrio anguillarum 775 are structurally and functionally related
The siderophore-mediated iron acquisition systems of Acinetobacter baumannii ATCC 19606 and Vibrio anguillarum 775 are structurally and functionally related
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DOI：
10.1099/mic.0.27371-0
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发表时间：
2004-11-01
期刊：
影响因子：
2.8
通讯作者：
Actis, LA
中科院分区：
文献类型：
--
作者：
Dorsey, CW;Tomaras, AP;Actis, LA
鲍曼不动杆菌型菌株ATCC 19606分泌一种与鱼类病原体鳗弧菌（Listonella anguillarum）产生的铁螯合剂鳗弧菌（anguibactin）高度相关的邻苯二酚类铁元素。本文报道了参与不动杆菌素介导的铁获取过程的基因和基因产物的初步表征。插入诱变导致了几个衍生物的分离，这些衍生物在含有铁螯合剂2,2'-二吡啶的培养基中生长的能力受到影响。其中一个插入破坏了一个基因，该基因编码一种被预测的外膜蛋白，名为BauA，与铁酰巴丁蛋白的受体FatA高度相似。Western blot分析证实了BauA与FatA的免疫学相关性。另一个转座子插入被定位到一个编码蛋白质的基因上，该蛋白质与FatD高度相似，FatD是anguibactin转运系统的渗透酶成分。进一步的DNA测序和核苷酸序列分析表明，这些鲍曼不动杆菌19606基因是包含bauDCEBA orf的多顺反子位点的一部分。虽然bauD、c、-B和-A的翻译产物与V. anguillarum的脂肪铁转运蛋白高度相关，但bauD的翻译产物与革兰氏阳性atp结合盒（ABC）转运系统的atp酶组分有关。整个基因座的两侧是编码AngU和AngN相关蛋白的基因，AngU和AngN是鳗鲡生物合成鳗鲡蛋白所需的蛋白质。这些蛋白质的相似性以及anguibactin和acinetoactin的结构相似性表明，这两种铁载体可以被两种细菌利用，这种可能性被铁载体利用的生物测定证实了。综上所述，这些结果表明，这些在不相关宿主中引起严重感染的病原体表达非常相似的铁载体介导的铁获取系统。
The Acinetobacter baumannii type strain, ATCC 19606, secretes acinetobactin, a catechol siderophore highly related to the iron chelator anguibactin produced by the fish pathogen Vibrio anguillarum (Listonella anguillarum). This paper reports the initial characterization of the genes and gene products involved in the acinetobactin-mediated iron-acquisition process. Insertional mutagenesis resulted in the isolation of several derivatives whose ability to grow in medium containing the iron chelator 2,2'-dipyridyl was affected. One of the insertions disrupted a gene encoding a predicted outer-membrane protein, named BauA, highly similar to FatA, the receptor for ferric anguilbactin. Immunological relatedness of BauA with FatA was confirmed by Western blot analysis. Another transposon insertion was mapped to a gene encoding a protein highly similar to FatD, the permease component of the anguibactin transport system. Further DNA sequencing and nucleotide sequence analysis revealed that these A. baumannii 19606 genes are part of a polycistronic locus that contains the bauDCEBA ORFs. While the translation products of bauD, -C, -B and -A are highly related to the V. anguillarum Fatl iron-transport proteins, the product of bauE is related to the ATPase component of Gram-positive ATP-binding cassette (ABC) transport systems. This entire locus is flanked by genes encoding predicted proteins related to AngU and AngN, V. anguillarum proteins required for the biosynthesis of anguibactin. These protein similarities, as well as the structural similarity of anguibactin and acinetobactin, suggested that these two siderophores could be utilized by both bacterial strains, a possibility that was confirmed by siderophore utilization bioassays. Taken together, these results demonstrate that these pathogens, which cause serious infections in unrelated hosts, express very similar siderophore-mediated iron-acquisition systems.