Laboratoire de Chimie Bactérienne, CNRS UPR-9043, Institut de Microbiologie de la Méditerranée, 31 Chemin Joseph Aiguier, 13009 Marseille, France.
Environ Microbiol. 2010 Oct;12(10):2846-57. doi: 10.1111/j.1462-2920.2010.02265.x.
Cobalt can be toxic and the way cells adapt to its presence is largely unknown. Here we carried out a transcriptomic analysis of Escherichia coli exposed to cobalt. A limited number of genes were either up- or downregulated. Upregulated genes include the isc and the nfuA genes encoding Fe/S biogenesis assisting factors, and the rcnA gene encoding a cobalt efflux system. Downregulated genes are implicated in anaerobic metabolism (narK, nirB, hybO, grcA), metal transport (feoB, nikA), sulfate/thiosulfate import (cysP), and one is of unknown function (yeeE). Cobalt regulation of isc, nfuA, hybO, cysP and yeeE genes was found to involve IscR, a Fe/S transcriptional regulator. Previously, the Suf Fe/S biogenesis machinery was found to be important for cobalt stress adaptation, but suf genes did not show up in the microarray analysis. Therefore, we used qRT-PCR analysis and found that cobalt induced the suf operon expression. Moreover, kinetic analysis of the cobalt-mediated induction of the suf operon expression allowed us to propose that cobalt toxicity is caused first by impaired Fe/S biogenesis, followed by decreased iron bioavailability and eventually oxidative stress.
钴可能有毒，细胞适应钴存在的方式在很大程度上是未知的。在这里，我们对暴露于钴的大肠杆菌进行了转录组分析。少数基因被上调或下调。上调的基因包括编码 Fe/S 生物发生辅助因子的 isc 和 nfuA 基因，以及编码钴外排系统的 rcnA 基因。下调的基因与厌氧代谢（narK、nirB、hybO、grcA）、金属转运（feoB、nikA）、硫酸盐/硫代硫酸盐导入（cysP）和一个未知功能的基因（yeeE）有关。发现钴对 isc、nfuA、hybO、cysP 和 yeeE 基因的调节涉及到 IscR，这是一种 Fe/S 转录调节剂。先前发现 Suf Fe/S 生物发生机制对于钴胁迫适应很重要，但 Suf 基因在微阵列分析中没有出现。因此，我们使用 qRT-PCR 分析发现钴诱导了 suf 操纵子的表达。此外，钴介导的 suf 操纵子表达诱导的动力学分析使我们能够提出钴毒性首先是由 Fe/S 生物发生受损引起的，随后是铁生物利用度降低，最终是氧化应激。
