The thioredoxin superfamily: redundancy, specificity, and gray-area genomics.
The thioredoxin superfamily: redundancy, specificity, and gray-area genomics.
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硫氧还蛋白超家族：冗余、特异性和灰色区域基因组学。
DOI：
10.1128/jb.181.5.1375-1379.1999
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发表时间：
1999
影响因子：
3.2
通讯作者：
Beckwith,J
中科院分区：
文献类型：
--
作者：
Aslund,F;Beckwith,J
当我们开始研究大肠杆菌碱性磷酸酶从细胞质中的输出时，硫醇-二硫化物氧化还原化学的问题还没有出现在我们的意识中。我们选择了这种周质酶，因为它似乎是一个很好的工具来表征蛋白质跨细胞质膜易位的机制。然而，我们对信号序列突变体的选择和分析使我们惊讶地发现，当碱性磷酸酶定位于细菌细胞质时，它是无酶活性的（32）。由于细胞质被认为是一个比周质还原性更强的环境，我们推断细胞质碱性磷酸酶活性的缺乏是由于蛋白质未能形成其两个必需的二硫键。我们后来证实，这种酶的细胞质形式确实缺乏二硫键（14），这些结果给我们提出了以前没有考虑过的问题。细胞质中是否有特定的蛋白质负责阻止不必要的二硫键形成？周质中是否存在催化这些键形成的特定蛋白质？我们能从遗传学的角度来探讨这些问题吗？通过提出这些问题，我们继续发展遗传选择，这可能有助于我们识别参与决定两个隔室蛋白质中半胱氨酸氧化态的蛋白质。这些努力的结果以及其他许多实验室的结果沿着让我们对一系列令人印象深刻的大肠杆菌大开眼界。属于硫氧还蛋白超家族一部分的大肠杆菌蛋白。此外，推进更深入到这个家庭的成员，表现出非常相似的结构的功能提出了一些问题的方向，必要的研究成功的功能基因组学。
Issues of thiol-disulfide redox chemistry were nowhere in our consciousness when we began to study the export of Escherichia coli alkaline phosphatase from the cytoplasm. We chose this periplasmic enzyme because it seemed an excellent tool for characterizing the mechanism of protein translocation across the cytoplasmic membrane. However, our selection and analysis of signal sequence mutants led us to the surprising discovery that alkaline phosphatase was enzymatically inactive when it was localized to the bacterial cytoplasm (32). Since the cytoplasm was reputedly a much more reducing environment than the periplasm, we reasoned that the lack of cytoplasmic alkaline phosphatase activity was due to the failure of the protein to form its two essential disulfide bonds. We later established that the cytoplasmic form of the enzyme did indeed lack disulfide bonds (14).These results presented us with questions we had not considered before. Were there specific proteins in the cytoplasm that were responsible for keeping unwanted disulfide bonds from forming? Were there specific proteins in the periplasm that catalyzed formation of these bonds? Could we approach these questions genetically? From posing these questions, we moved on to develop genetic selections that might help us identify proteins involved in determining the oxidation state of cysteines in proteins of the two compartments. The results of these efforts along with those of a number of other labs have opened our eyes to an impressive array of E. coli proteins that are part of the thioredoxin superfamily. Furthermore, pushing ever deeper into the functions of members of this family which exhibit very similar structures raises a number of issues about the directions necessary for the success of studies in functional genomics.