Co-evolution of multipartite interactions between an extended tmRNA tag and a robust Lon protease in Mycoplasma.
Co-evolution of multipartite interactions between an extended tmRNA tag and a robust Lon protease in Mycoplasma.
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DOI：
10.1111/j.1365-2958.2009.06923.x
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发表时间：
2009-12
影响因子：
3.6
通讯作者：
Karzai AW
中科院分区：
文献类型：
--
作者：
Ge Z;Karzai AW
缺少框内终止密码子的信使RNA促进核糖体停滞和异常和潜在有害多肽的积累。SmpB-tmRNA质量控制系统已经发展到解决与不停止mRNA相关的问题，通过拯救停滞的核糖体并将肽标签添加到相关蛋白质的C末端，标记它们进行蛋白水解。在大肠在大肠杆菌中，ClpXP系统是处理tmRNA标记蛋白的主要贡献者。我们已经表明，AAA+ Lon蛋白酶也可以降解tmRNA标记的蛋白质，但效率低得多。在这里，我们提出了一个独特的情况下，增强识别和降解的扩展肺炎支原体（MP）tmRNA标签的MP-Lon蛋白酶。我们证明MP-Lon可以有效地和选择性地降解MP-tmRNA标记的蛋白质。最重要的是，我们的研究表明，较大的（27个氨基酸长）MP-tmRNA标签包含多个离散的信号转导基序，用于有效识别和快速降解的Lon。我们认为，MP-Lon和扩展的MP-tmRNA标签之间的更高亲和力的多组分相互作用是从预先存在的较弱相互作用共同进化而来的，正如Lon在E.大肠杆菌，以更好地实现MP-Lon作为唯一的可溶性细胞质蛋白酶负责降解tmRNA标记的蛋白质的功能。
Messenger RNAs that lack in-frame stop codons promote ribosome stalling and accumulation of aberrant and potentially harmful polypeptides. The SmpB-tmRNA quality control system has evolved to solve problems associated with nonstop mRNAs, by rescuing stalled ribosomes and directing the addition of a peptide tag to the C-termini of the associated proteins, marking them for proteolysis. In E. coli, the ClpXP system is the major contributor to disposal of tmRNA tagged proteins. We have shown that the AAA+ Lon protease can also degrade tmRNA tagged proteins, but with much lower efficiency. Here, we present a unique case of enhanced recognition and degradation of an extended Mycoplasma pneumoniae (MP) tmRNA tag by the MP-Lon protease. We demonstrate that MP-Lon can efficiently and selectively degrade MP-tmRNA tagged proteins. Most significantly, our studies reveal that the larger (27 amino acid long) MP-tmRNA tag contains multiple discrete signaling motifs for efficient recognition and rapid degradation by Lon. We propose that higher affinity multipartite interactions between MP-Lon and the extended MP-tmRNA tag have co-evolved from pre-existing weaker interactions, as exhibited by Lon in E. coli, to better fulfill the function of MP-Lon as the sole soluble cytoplasmic protease responsible for the degradation of tmRNA tagged proteins.