The Bradyrhizobium japonicum fsrB gene is essential for utilization of structurally diverse ferric siderophores to fulfill its nutritional iron requirement.
The Bradyrhizobium japonicum fsrB gene is essential for utilization of structurally diverse ferric siderophores to fulfill its nutritional iron requirement.
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DOI：
10.1111/mmi.15028
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发表时间：
2023-03
影响因子：
3.6
通讯作者：
O'Brian, Mark R.
中科院分区：
文献类型：
--
作者：
Ong, Alasteir;O'Brian, Mark R.
在细菌慢生根瘤菌（Bradyrhizobium japonicum）中，从铁铁载体吸收铁涉及选择性外膜蛋白和非选择性周质膜和细胞质膜组分，其容纳许多结构不同的铁载体。铁通过亚铁（Fe 2+）转运蛋白FeoAB穿过细胞质膜，但尚未描述其他非选择性组分。在这里，我们确定fsrB作为一个铁调节的基因所需的铁螯合物的儿茶酚盐和羟酸盐型铁载体的增长，但不是无机铁或血红素。利用非生理铁螯合剂EDDHA作为铁源也依赖于fSRB。与野生型相比，fsr B突变体对铁胺B、铁色素或肠杆菌素结合的~（55）Fe ~（3+）的摄取活性严重降低。用质粒携带的E. coli fhuCDB铁色素转运基因，表明FsrB活性发生在周质而不是细胞质中。一个fsrB突变体是铁还原酶活性缺陷。fsrB突变体中铁载体的脱金属活性也有缺陷。总的来说，这些数据支持一个模型，即FSRB是需要减少铁和它的解离从铁载体在周质中，然后通过运输的亚铁离子进入细胞质的FeoAB。
In the bacterium Bradyrhizobium japonicum, iron uptake from ferric siderophores involves selective outer membrane proteins and non-selective periplasmic and cytoplasmic membrane components that accommodate numerous structurally diverse siderophores. Iron traverses the cytoplasmic membrane through the ferrous (Fe2+) transporter FeoAB, but other non-selective components have not been described. Here, we identify fsrB as an iron-regulated gene required for growth on iron chelates of catecholate- and hydroxymate-type siderophores, but not on inorganic iron or heme. Utilization of the non-physiological iron chelator EDDHA as an iron source was also dependent on fsrB. Uptake activities of 55Fe3+ bound to ferrioxamine B, ferrichrome or enterobactin were severely diminished in the fsrB mutant compared with the wild type. Growth of the fsrB or feoB strains on ferrichrome were rescued with plasmid-borne E. coli fhuCDB ferrichrome transport genes, suggesting that FsrB activity occurs in the periplasm rather than the cytoplasm. An fsrB mutant was defective in ferric reductase activity. Demetallation activities of ferric siderophores were deficient in an fsrB mutant as well. Collectively, the data support a model whereby FsrB is required for reduction of iron and its dissociation from the siderophore in the periplasm, followed by transport of the ferrous ion into the cytoplasm by FeoAB.
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影响因子：
3.6
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通讯作者：
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