Degradation of SsrA-tagged proteins in streptococci.
Degradation of SsrA-tagged proteins in streptococci.
复制标题
链球菌中 SsrA 标记蛋白的降解。
DOI：
10.1099/mic.0.000048
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发表时间：
2015
期刊：
影响因子：
--
通讯作者：
Biswas,Indranil
中科院分区：
文献类型：
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作者：
Tao,Liang;Biswas,Indranil
在原核生物中，一种称为 tmRNA 的保守小 RNA 分子可以从因稀有密码子或降解 mRNA 的存在而异常截短的蛋白质中拯救核糖体。在救援过程中，由 tmRNA 编码的肽标签 (SsrA) 被共翻译添加到截短的多肽中，从而靶向这些蛋白质进行蛋白水解降解。在大肠杆菌中，ClpXP 和 ClpAP 蛋白酶主要降解 SsrA 标记的蛋白质。其他蛋白酶如 Lon 和 FtsH 也参与大肠杆菌中的降解。大肠杆菌。然而，在枯草芽孢杆菌中，ClpXP 是降解 SsrA 标记蛋白的主要蛋白酶。除了 ClpXP 负责大部分降解之外，链球菌中 SsrA 标记蛋白的降解尚不清楚。在这里我们表明，在变形链球菌中，除了 ClpXP 之外，另外两种 Clp 复合物 ClpCP 和 ClpEP 也参与降解。我们还发现 ClpCP 和 ClpEP 介导的 SsrA 标记底物的蛋白水解是由热应激诱导的。由于 ClpCP 和 ClpEP 蛋白在链球菌中高度保守，我们预测 ClpEP 和 ClpCP 介导的 SsrA 标记蛋白降解可能在其他链球菌中发挥作用。
In prokaryotes, a conserved small RNA molecule, called tmRNA, rescues ribosomes from proteins that are abnormally truncated due to the presence of rare codons or degraded mRNA. During the rescue process, a peptide tag (SsrA) encoded by tmRNA is cotranslationally added to the truncated polypeptides, thereby targeting these proteins for proteolytic degradation. InEscherichia coli, ClpXP and ClpAP proteases primarily degrade SsrA-tagged proteins. Other proteases such as Lon and FtsH also participate in the degradation inE. coli. However, inBacillus subtilis, ClpXP is the major protease that degrades the SsrA-tagged proteins. Degradation of SsrA-tagged protein in streptococci is not well understood except that ClpXP is responsible for the majority of the degradation. Here we show that inStreptococcus mutans, in addition to ClpXP, two other Clp complexes, ClpCP and ClpEP, are also involved in the degradation. We also found that ClpCP- and ClpEP-mediated proteolysis of SsrA-tagged substrates is induced by heat stress. As ClpCP and ClpEP proteins are highly conserved in streptococci, we predicted that ClpEP- and ClpCP-mediated degradation of SsrA-tagged proteins might be operational in other streptococci.