IRON(III) HYDROXAMATE TRANSPORT IN ESCHERICHIA-COLI K-12 - FHUB-MEDIATED MEMBRANE ASSOCIATION OF THE FHUC PROTEIN AND NEGATIVE COMPLEMENTATION OF FHUC MUTANTS
IRON(III) HYDROXAMATE TRANSPORT IN ESCHERICHIA-COLI K-12 - FHUB-MEDIATED MEMBRANE ASSOCIATION OF THE FHUC PROTEIN AND NEGATIVE COMPLEMENTATION OF FHUC MUTANTS
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DOI：
10.1128/jb.174.7.2305-2311.1992
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发表时间：
1992-04-01
影响因子：
3.2
通讯作者：
BRAUN, V
中科院分区：
文献类型：
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作者：
SCHULTZHAUSER, G;KOSTER, W;BRAUN, V
异羟肟酸铁 (III) 跨细胞质膜的转运由高度疏水性的 FhuB 蛋白和膜相关的 FhuC 蛋白催化，其中包含典型的 ATP 结合域。通过使用抗 FhuC 抗体的免疫电子显微镜证明了两种蛋白质之间的相互作用，这表明 FhuB 介导的 FhuC 与细胞质膜的结合。此外，在 ATP 结合域中携带单个氨基酸取代的无活性 FhuC 衍生物抑制了野生型 FhuC 转运活性，这种活性要么是由于突变的 FhuC 衍生物从 FhuB 上置换了活性 FhuC，要么是由于野生型和突变的 FhuC 蛋白之间形成了混合的无活性 FhuC 多聚体。含有内部缺失和插入的无活性FhuC衍生物没有表现出表型抑制，表明构象改变使得FhuC衍生物无法取代野生型FhuC。结论是，FhuC 和 FhuB 之间的物理相互作用意味着两种蛋白在异羟肟酸铁 (III) 通过细胞质膜的转运中具有协调活性。
Iron(III) hydroxamate transport across the cytoplasmic membrane is catalyzed by the very hydrophobic FhuB protein and the membrane-associated FhuC protein, which contains typical ATP-binding domains. Interaction between the two proteins was demonstrated by immunoelectron microscopy with anti-FhuC antibodies, which showed FhuB-mediated association of FhuC with the cytoplasmic membrane. In addition, inactive FhuC derivatives carrying single amino acid replacements in the ATP-binding domains suppressed wild-type FhuC transport activity, which arose either from displacement of active FhuC from FhuB by the mutated FhuC derivatives or from the formation of mixed inactive FhuC multimers between wild-type and mutated FhuC proteins. Inactive FhuC derivatives containing internal deletions and insertions showed no phenotypic suppression, indicating conformational alterations that rendered the FhuC derivatives unable to displace wild-type FhuC. It is concluded that the physical interaction between FhuC and FhuB implies a coordinate activity of both proteins in the transport of iron(III) hydroxamates through the cytoplasmic membrane.