Laboratoire de Chimie Bactérienne, UMR 7283 Aix-Marseille Université-CNRS, Institut de Microbiologie de la Méditerranée, 31 Chemin Joseph Aiguier, 13009 Marseille, France.
Mol Microbiol. 2013 Feb;87(3):493-508. doi: 10.1111/mmi.12135. Epub 2013 Jan 16.
The multi-proteins Isc and Suf systems catalyse the biogenesis of [Fe-S] proteins. Here we investigate how NsrR and IscR, transcriptional regulators that sense NO and [Fe-S] homeostasis, acquire their [Fe-S] clusters under both normal and iron limitation conditions. Clusters directed at the apo-NsrR and apo-IscR proteins are built on either of the two scaffolds, IscU or SufB. However, differences arise in [Fe-S] delivery steps. In the case of NsrR, scaffolds deliver clusters to either one of the two ATCs, IscA and SufA, and, subsequently, to the 'non-Isc non-Suf' ATC, ErpA. Nevertheless, a high level of SufA can bypass the requirement for ErpA. In the case of IscR, several routes occur. One does not include assistance of any ATC. Others implicate ATCs IscA or ErpA, but, surprisingly, SufA was totally absent from any IscR maturation pathways. Both IscR and NsrR have the intrinsic capacity to sense iron limitation. However, NsrR appeared to be efficiently matured by Isc and Suf, thereby preventing NsrR to act as a physiologically relevant iron sensor. This work emphasizes that different maturation pathways arise as a function of the apo-target considered, possibly in relation with the type of cluster, [2Fe-2S] versus [4Fe-4S], it binds.
多蛋白 Isc 和 Suf 系统催化 [Fe-S] 蛋白的生物发生。在这里，我们研究了转录调节剂 NsrR 和 IscR 如何在正常和铁限制条件下感应 NO 和 [Fe-S] 稳态来获取其 [Fe-S] 簇。针对 apo-NsrR 和 apo-IscR 蛋白的簇构建在两个支架 IscU 或 SufB 之一上。然而，在 [Fe-S] 传递步骤中存在差异。对于 NsrR，支架将簇传递到两个 ATCs（IscA 和 SufA）之一，然后传递到“非 Isc 非 Suf”ATC ErpA。然而，高水平的 SufA 可以绕过对 ErpA 的需求。对于 IscR，存在几种途径。一种途径不包括任何 ATC 的辅助。其他途径涉及 ATC IscA 或 ErpA，但令人惊讶的是，SufA 完全不存在于任何 IscR 成熟途径中。IscR 和 NsrR 都具有感应铁限制的内在能力。然而，NsrR 似乎被 Isc 和 Suf 有效地成熟，从而防止 NsrR 作为生理相关的铁传感器发挥作用。这项工作强调了不同的成熟途径是作为考虑的 apo 靶标的函数而出现的，可能与它结合的簇的类型有关，[2Fe-2S] 与 [4Fe-4S]。
