Identification of protein stability determinants in chloroplasts.
Identification of protein stability determinants in chloroplasts.
复制标题
DOI：
10.1111/j.1365-313x.2010.04268.x
复制
发表时间：
2010-08
期刊：
影响因子：
--
通讯作者：
Bock R
中科院分区：
文献类型：
--
作者：
Apel W;Schulze WX;Bock R
虽然叶绿体蛋白质稳定性长期以来被认为是光合作用和基因表达中翻译后调节的主要水平，但决定质体中蛋白质稳定性的因素在很大程度上是未知的。在这里，我们已经确定了在体内的稳定性决定因素，通过生产转基因叶绿体表达的报告蛋白，其N-和C-末端进行了系统的修改。我们发现，主要的稳定性决定因素位于N-末端。此外，在起始剂甲硫氨酸之后的位置中的所有20个氨基酸的测试揭示了蛋白质稳定性的强烈差异，并且表明倒数第二个N-末端氨基酸残基在确定蛋白质半衰期中的重要作用。我们认为质体蛋白质的稳定性主要由三个因素决定：（i）甲硫氨酸氨肽酶（去除起始甲硫氨酸并暴露倒数第二个N-末端氨基酸残基的酶）的作用，（ii）N-末端规则样蛋白质降解途径，以及（iii）N-末端区域中的额外序列决定簇。
Although chloroplast protein stability has long been recognised as a major level of post-translational regulation in photosynthesis and gene expression, the factors determining protein stability in plastids are largely unknown. Here, we have identified stability determinants in vivo by producing plants with transgenic chloroplasts that express a reporter protein whose N- and C-termini were systematically modified. We found that major stability determinants are located in the N-terminus. Moreover, testing of all 20 amino acids in the position after the initiator methionine revealed strong differences in protein stability and indicated an important role of the penultimate N-terminal amino acid residue in determining the protein half life. We propose that the stability of plastid proteins is largely determined by three factors: (i) the action of methionine aminopeptidase (the enzyme that removes the initiator methionine and exposes the penultimate N-terminal amino acid residue), (ii) an N-end rule-like protein degradation pathway, and (iii) additional sequence determinants in the N-terminal region.