Fecker L, Braun V
J Bacteriol. 1983 Dec;156(3):1301-14. doi: 10.1128/jb.156.3.1301-1314.1983.
Each of the four hydroxamate compounds, ferrichrome, aerobactin, rhodotorulic acid, and coprogen, known to transport ferric iron into Escherichia coli requires a specific outer membrane receptor protein. In addition, common transport functions for all four ferric hydroxamate compounds have been identified in the 3.5-min region of the linkage map and designated fhu. The fhu region was cloned into pBR322. By restriction analysis, Tn5 insertion mutations, and complementation studies between plasmid fragments and chromosomal mutants at least four loci in the order fhuA fhuC fhuD fhuB were found. The genetic products were determined in maxicells and minicells. fhuA codes for the known 78,000-dalton receptor protein and the 81,000-dalton precursor in the outer membrane, fhuC codes for a 30,000-dalton protein, and fhuD encodes a 26,000-dalton protein in the cytoplasmic membrane. No protein(s) could be assigned to the fhuB region. Truncated proteins derived from partial fhuA genes (68,000, 42,000, and 39,000 daltons) and a partial fhuD gene (24,000 daltons) and the strong polar effect on the expression of the genes indicated the direction of transcription to be from fhuA to fhuD.
四种异羟肟酸化合物，即高铁色素、气杆菌素、红酵母氨酸和粪生绿素，已知它们能将三价铁转运到大肠杆菌中，每种化合物都需要一种特定的外膜受体蛋白。此外，已在连锁图谱的3.5分钟区域鉴定出所有四种异羟肟酸铁化合物的共同转运功能，并将其命名为fhu。fhu区域被克隆到pBR322中。通过限制性分析、Tn5插入突变以及质粒片段与染色体突变体之间的互补研究，发现了至少四个按fhuA、fhuC、fhuD、fhuB顺序排列的基因座。在最大细胞和最小细胞中确定了基因产物。fhuA编码外膜中已知的78,000道尔顿受体蛋白和81,000道尔顿前体，fhuC编码一种30,000道尔顿的蛋白，fhuD在细胞质膜中编码一种26,000道尔顿的蛋白。无法将任何蛋白质定位到fhuB区域。源自部分fhuA基因（68,000、42,000和39,000道尔顿）和部分fhuD基因（24,000道尔顿）的截短蛋白以及对基因表达的强极性效应表明转录方向是从fhuA到fhuD。
