The Bradyrhizobium japonicum exporter ExsFGH is involved in efflux of ferric xenosiderophores from the periplasm.
The Bradyrhizobium japonicum exporter ExsFGH is involved in efflux of ferric xenosiderophores from the periplasm.
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DOI：
10.1371/journal.pone.0296306
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发表时间：
2024
期刊：
影响因子：
3.7
通讯作者：
中科院分区：
文献类型：
--
作者：
革兰氏阴性菌慢生根瘤菌（Bradyrhizobium japonicum）可以从环境中吸收结构不同的铁载体（异铁载体），以满足其营养铁的需求。运输到周质中的铁载体结合的铁被FsrB还原为亚铁形式，从铁载体解离，然后游离离子通过亚铁转运蛋白FeoAB运输到细胞质中。在这里，我们确定了RND家族的出口基因exsFG和exsH在选择的第二个站点抑制突变体，恢复生长的fSRB突变体的铁载体ferrichrome或ferrioxamine。在fSRB突变体中观察到的来自55 Fe标记的铁色素或铁胺的低水平放射性标记积累在fSRB exsG突变体中恢复至野生型水平。此外，exsG突变体积累更多的放射性标记从55铁标记的铁载体比野生型，但从无机55铁的放射性标记的积累是相似的两个菌株。因此，ExsFGH输出铁载体结合的铁，但不输出无机铁。被拯救的fsrB exsG突变体需要feoB生长，表明ExsFGH作用于周质中的那些铁载体。exsG突变体比野生型对铁载体抗生素白霉素更敏感，而fsrB突变体更耐药。这表明ExsFGH通常输出高铁白霉素。B。日本血吸虫对许多抗生素具有天然抗性。exsG菌株对四环素非常敏感，但对其他六种测试抗生素不敏感。我们的结论是，ExsFGH是一个广泛的底物出口商，需要维持铁载体在周质中的稳态。
The gram-negative bacterium Bradyrhizobium japonicum can take up structurally dissimilar ferric siderophores from the environment (xenosiderophores) to meet its nutritional iron requirements. Siderophore-bound iron transported into the periplasm is reduced to the ferrous form by FsrB, dissociated from the siderophore and the free ion is then transported into the cytoplasm by the ferrous iron transporter FeoAB. Here, we identified the RND family exporter genes exsFG and exsH in a selection for secondary site suppressor mutants that restore growth of an fsrB mutant on the siderophores ferrichrome or ferrioxamine. The low level of radiolabel accumulation from 55Fe-labeled ferrichrome or ferrioxamine observed in the fsrB mutant was restored to wild type levels in the fsrB exsG mutant. Moreover, the exsG mutant accumulated more radiolabel from the 55Fe-labeled siderophores than the wild type, but radiolabel accumulation from inorganic 55Fe was similar in the two strains. Thus, ExsFGH exports siderophore-bound iron, but not inorganic iron. The rescued fsrB exsG mutant required feoB for growth, indicating that ExsFGH acts on those siderophores in the periplasm. The exsG mutant was more sensitive to the siderophore antibiotic albomycin than the wild type, whereas the fsrB mutant was more resistant. This suggests ExsFGH normally exports ferrated albomycin. B. japonicum is naturally resistant to many antibiotics. The exsG strain was very sensitive to tetracycline, but not to six other antibiotics tested. We conclude that ExsFGH is a broad substrate exporter that is needed to maintain siderophore homeostasis in the periplasm.
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影响因子：
3.6
作者：
Chatterjee A;O'Brian MR
通讯作者：
O'Brian MR
DOI：
10.1111/j.1432-1033.1979.tb13283.x
发表时间：
1979-01-01
期刊：
EUROPEAN JOURNAL OF BIOCHEMISTRY
影响因子：
--
作者：
HARTMANN, A;FIEDLER, HP;BRAUN, V
通讯作者：
BRAUN, V
影响因子：
3.6
作者：
Nienaber, A;Hennecke, H;Fischer, HM
通讯作者：
Fischer, HM
DOI：
10.1073/pnas.2101952118
发表时间：
2021-08-24
影响因子：
11.1
作者：
Josts, Inokentijs;Veith, Katharina;Tidow, Henning
通讯作者：
Tidow, Henning
DOI：
10.1016/j.bbapap.2008.10.004
发表时间：
2009-05
期刊：
Biochimica et biophysica acta
影响因子：
--
作者：
Nikaido H;Takatsuka Y
通讯作者：
Takatsuka Y