Molecular analysis of the copper-transporting efflux system CusCFBA of Escherichia coli
Molecular analysis of the copper-transporting efflux system CusCFBA of Escherichia coli
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DOI：
10.1128/jb.185.13.3804-3812.2003
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发表时间：
2003-07-01
影响因子：
3.2
通讯作者：
Nies, DH
中科院分区：
文献类型：
--
作者：
Franke, S;Grass, G;Nies, DH
大肠杆菌的cus决定簇编码CusCFBA蛋白，其通过阳离子流出介导对铜和银的抗性。CusA和CusB对铜电阻是必不可少的，CusC和CusF对全电阻是必需的。在CusA中用异亮氨酸替换甲硫氨酸残基573、623和672导致铜抗性丧失，证明了它们的功能重要性。该蛋白质的几个其他甲硫氨酸残基的取代没有任何影响。小的10-kDa的蛋白质CusF（以前YlcC）被证明是一个周质蛋白。CusF结合每个多肽一个铜。粉红色CusF铜蛋白复合物在约510 nm处显示出最大吸收。CusF的甲硫氨酸残基参与铜结合，如定点突变所示。在酵母双杂交测定中，CusF与CusB和CusC多肽相互作用。与其他研究充分的CBA型重金属外排系统相比，Cus被证明是一个四分抗性系统，涉及新的周质铜结合蛋白CusF。这些数据提供了额外的证据的假设，铜（I）是直接从周质跨外膜的Cus复杂。
The cus determinant of Escherichia coli encodes the CusCFBA proteins that mediate resistance to copper and silver by cation efflux. CusA and CusB were essential for copper resistance, and CusC and CusF were required for full resistance. Replacements of methionine residues 573, 623, and 672 with isoleucine in CusA resulted in loss of copper resistance, demonstrating their functional importance. Substitutions for several other methionine residues of this protein did not have any effect. The small 10-kDa protein CusF (previously YlcC) was shown to be a periplasmic protein. CusF bound one copper per polypeptide. The pink CusF copper protein complex exhibited an absorption maximum at around 510 nm. Methionine residues of CusF were involved in copper binding as shown by site-directed mutagenesis. CusF interacted with CusB and CusC polypeptides in a yeast two-hybrid assay. In contrast to other well-studied CBA-type heavy metal efflux systems, Cus was shown to be a tetrapartite resistance system that involves the novel periplasmic copper-binding protein CusF. These data provide additional evidence for the hypothesis that Cu(I) is directly transported from the periplasm across the outer membrane by the Cus complex.