Control of peptide product sizes by the energy-dependent protease ClpAP
Control of peptide product sizes by the energy-dependent protease ClpAP
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DOI：
10.1021/bi0505060
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发表时间：
2005-10-25
期刊：
影响因子：
2.9
通讯作者：
Licht, S
中科院分区：
文献类型：
--
作者：
Choi, KH;Licht, S
加工性蛋白酶可以解折叠蛋白质并将其切割成具有特征大小的片段。控制产品尺寸的详细机制仍有疑问。控制产物大小的一种可能的机制是将未折叠的多肽以限定长度的单位移位到蛋白酶活性位点。我们已经研究了ClpAP，一种来自大肠杆菌的能量依赖性蛋白酶，控制其肽产物大小的机制。我们表明，ClpAP产生的肽产品的大小分布，具有明显的峰在6-8个氨基酸残基的肽长度。该产物大小分布与先前观察到的蛋白酶体相似，对干扰易位或蛋白水解的扰动具有稳健性。为了解释这些结果，我们提出了一种机制，易位交替与蛋白水解，允许肽或多或少的统一长度被切割procectin从一个易位基板。为了估计ClpAP催化的产物尺寸测量的速率和能量效率，我们应用信息论来量化产物尺寸控制的精确程度。这种分析也可能被证明是有用的，在表征其他蛋白酶和核酸酶的机制，如蛋白酶体和切丁酶，控制其产品的大小。
Processive proteases can unfold proteins and cleave them into fragments of a characteristic size. The detailed mechanism by which product sizes are controlled is still in question. One possible mechanism for the control of product sizes would be translocation of unfolded polypeptides to the protease active sites in units of defined length. We have investigated the mechanism by which ClpAP, an energy-dependent protease from Escherichia coli, controls the sizes of its peptide products. We show that ClpAP generates peptide products with a distribution of sizes that has a pronounced peak at a peptide length of 6-8 amino acid residues. This product size distribution, which is similar to that observed previously for the proteasome, is robust to perturbations that interfere with translocation or proteolysis. To explain these results, we propose a mechanism in which translocation alternates with proteolysis, allowing peptides of more or less uniform length to be cleaved processively from a translocating substrate. To estimate the rate and energy efficiency of ClpAP-catalyzed measurements of product sizes, we apply information theory to quantify how precisely the product sizes are controlled. This analysis may also prove to be useful in characterizing the mechanisms of other proteases and nucleases, such as the proteasome and Dicer, which control the sizes of their products.