Radiation response in Deinococcus deserti: IrrE is a metalloprotease that cleaves repressor protein DdrO
Radiation response in Deinococcus deserti: IrrE is a metalloprotease that cleaves repressor protein DdrO
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DOI：
10.1111/mmi.12774
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发表时间：
2014-10-01
影响因子：
3.6
通讯作者：
de Groot, Arjan
中科院分区：
文献类型：
--
作者：
Ludanyi, Monika;Blanchard, Laurence;de Groot, Arjan
异常球菌以其极端的辐射耐受性而闻名。IrrE蛋白被证明是辐射耐受性所必需的，并且以一种未阐明的方式，诱导了许多对辐射作出反应的基因，包括recA和其他DNA修复基因。早期的研究表明IrrE可能是一种锌肽酶，但蛋白水解活性未得到证实。在这里，使用几个在体内和体外实验，IrrE从Deinococcus deserti被发现与DdrO，一个预测的调节器编码的辐射诱导的基因，是，像IrrE，高度保守的异常球菌。此外，IrrE被发现在体外切割DdrO和当蛋白质在大肠杆菌中共表达时。在金属螯合剂EDTA的存在下或当IrrE在金属肽酶的保守活性位点基序中含有突变时，未观察到这种切割。In D. deserti，在暴露于辐射后观察到IrrE依赖的DdrO裂解。此外，DdrO依赖的抑制辐射诱导的基因的启动子显示。这些结果表明，IrrE是一种金属蛋白酶，我们建议，IrrE介导的切割失活阻遏蛋白DdrO，导致异常球菌暴露于辐射后的修复和生存所需的各种基因的转录诱导。
Deinococcus bacteria are famous for their extreme radiation tolerance. The IrrE protein was shown to be essential for radiation tolerance and, in an unelucidated manner, for induction of a number of genes in response to radiation, including recA and other DNA repair genes. Earlier studies indicated that IrrE could be a zinc peptidase, but proteolytic activity was not demonstrated. Here, using several in vivo and in vitro experiments, IrrE from Deinococcus deserti was found to interact with DdrO, a predicted regulator encoded by a radiation-induced gene that is, like irrE, highly conserved in Deinococcus. Moreover, IrrE was found to cleave DdrOin vitro and when the proteins were coexpressed in Escherichia coli. This cleavage was not observed in the presence of metal chelator EDTA or when IrrE contains a mutation in the conserved active-site motif of metallopeptidases. In D. deserti, IrrE-dependent cleavage of DdrO was observed after exposure to radiation. Furthermore, DdrO-dependent repression of the promoter of a radiation-induced gene was shown. These results demonstrate that IrrE is a metalloprotease and we propose that IrrE-mediated cleavage inactivates repressor protein DdrO, leading to transcriptional induction of various genes required for repair and survival after exposure of Deinococcus to radiation.