Proteasome-mediated degradation of cotranslationally damaged proteins involves translation elongation factor 1A
Proteasome-mediated degradation of cotranslationally damaged proteins involves translation elongation factor 1A
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DOI：
10.1128/mcb.25.1.403-413.2005
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发表时间：
2005-01-01
影响因子：
5.3
通讯作者：
Madura, M
中科院分区：
文献类型：
--
作者：
Chuang, SM;Chen, L;Madura, M
RAD23和Rpn10在蛋白酶体识别泛素化蛋白的过程中起着协同作用，这两种蛋白的缺失会导致生长和蛋白降解缺陷。然而，RAD23和Rpn10的生理靶点还没有很好地确定。我们报告了rad23Delta rpn10Delta在翻译抑制剂存在的情况下不能生长，这种敏感性被翻译延伸因子1A(EEF1A)抑制。这一发现表明RAD23和Rpn10在翻译质量控制中发挥了作用。某些抑制剂会增加蛋白质合成过程中的翻译错误，并导致截短的多肽链的释放。这种影响也可以通过耗尽ATP来模仿。我们确定eEF1a在ATP耗尽后与泛素化蛋白和蛋白酶体相互作用。EEF1a与蛋白酶体亚基Rpt1相互作用，rpt1缺乏新生受损蛋白的周转。EEF1a突变体(eEFIA(D156N))对翻译抑制剂具有高度抗性，在清除受损蛋白质方面要有效得多，并在未处理细胞的蛋白酶体中检测到该突变。我们认为eEF1A非常适合于检测和促进受损蛋白质的降解，因为它在翻译延伸中起着核心作用。我们的发现为确定细胞蛋白质是如何共翻译降解的提供了机制基础。
Rad23 and Rpn10 play synergistic roles in the recognition of ubiquitinated proteins by the proteasome, and loss of both proteins causes growth and proteolytic defects. However, the physiological targets of Rad23 and Rpn10 have not been well defined. We report that rad23Delta rpn10Delta is unable to grow in the presence of translation inhibitors, and this sensitivity was suppressed by translation elongation factor 1A (eEF1A). This discovery suggested that Rad23 and Rpn10 perform a role in translation quality control. Certain inhibitors increase translation errors during protein synthesis and cause the release of truncated polypeptide chains. This effect can also be mimicked by ATP depletion. We determined that eEF1A interacted with ubiquitinated proteins and the proteasome following ATP depletion. eEF1A interacted with the proteasome subunit Rpt1, and the turnover of nascent damaged proteins was deficient in rpt1. An eEF1A mutant (eEFIA(D156N)) that conferred hyperresistance to translation inhibitors was much more effective at eliminating damaged proteins and was detected in proteasomes in untreated cells. We propose that eEF1A is well suited to detect and promote degradation of damaged proteins because of its central role in translation elongation. Our findings provide a mechanistic foundation for defining how cellular proteins are degraded cotranslationally.