Iron acquisition system of Sphingobium sp. strain SYK-6, a degrader of lignin-derived aromatic compounds
Iron acquisition system of Sphingobium sp. strain SYK-6, a degrader of lignin-derived aromatic compounds
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DOI：
10.1038/s41598-020-68984-2
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发表时间：
2020-07-22
影响因子：
4.6
通讯作者：
Masai, Eiji
中科院分区：
文献类型：
--
作者：
Fujita, Masaya;Sakumoto, Taichi;Masai, Eiji
铁是所有生物体的必需元素，在细菌降解难降解的芳香族化合物中作为酶的辅因子。细菌家族鞘氨醇单胞菌科包括多种降解柠檬酸芳香族化合物的细菌，然而，对其铁获取系统知之甚少。在这里，我们研究了铁收购系统的模式细菌能够降解木质素衍生的芳烃，鞘氨醇菌属菌株SYK-6。对SYK-6突变体的分析表明，FiuA（SLG_34550），一种TonB依赖性受体（TBDR），是主要的外膜铁转运蛋白。由SLG_04340、SLG_04380和SLG_10860编码的另外三种TBDR也参与铁摄取，并且tonB 2（SLG_34540）是构成Ton复合物的六种tonB之一，其能够实现TBDR介导的转运，对于铁摄取至关重要。二价铁转运蛋白FeoB（SLG_36840）在跨内膜的铁摄取中起重要作用。大多数铁吸收基因的启动子活性在铁限制条件下被诱导，并且它们的调节由编码铁吸收调节剂Fur的SLG_29410控制。虽然feoB，在所有的铁吸收基因鉴定是高度保守的鞘氨醇单胞菌菌株，外膜转运蛋白似乎是多样化的。阐明铁收购系统的承诺更好地了解芳香族化合物的细菌降解机制。
Iron, an essential element for all organisms, acts as a cofactor of enzymes in bacterial degradation of recalcitrant aromatic compounds. The bacterial family, Sphingomonadaceae comprises various degraders of recalcitrant aromatic compounds; however, little is known about their iron acquisition system. Here, we investigated the iron acquisition system in a model bacterium capable of degrading lignin-derived aromatics, Sphingobium sp. strain SYK-6. Analyses of SYK-6 mutants revealed that FiuA (SLG_34550), a TonB-dependent receptor (TBDR), was the major outer membrane iron transporter. Three other TBDRs encoded by SLG_04340, SLG_04380, and SLG_10860 also participated in iron uptake, and tonB2 (SLG_34540), one of the six tonB comprising the Ton complex which enables TBDR-mediated transport was critical for iron uptake. The ferrous iron transporter FeoB (SLG_36840) played an important role in iron uptake across the inner membrane. The promoter activities of most of the iron uptake genes were induced under iron-limited conditions, and their regulation is controlled by SLG_29410 encoding the ferric uptake regulator, Fur. Although feoB, among all the iron uptake genes identified is highly conserved in Sphingomonad strains, the outer membrane transporters seem to be diversified. Elucidation of the iron acquisition system promises better understanding of the bacterial degradation mechanisms of aromatic compounds.