Signal peptide etiquette during assembly of a complex respiratory enzyme.
Signal peptide etiquette during assembly of a complex respiratory enzyme.
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复杂呼吸酶组装过程中的信号肽礼仪。
DOI：
10.1111/mmi.12373
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发表时间：
2013
影响因子：
3.6
通讯作者：
James MJ
中科院分区：
文献类型：
--
作者：
James MJ
鼠伤寒沙门菌是一种革兰氏阴性病原体，能够通过一些终端电子受体进行呼吸。四硫酸还原酶在感染过程中很重要，由ttrbcaoperon编码，其中TtrA和TtrB是含金属辅助因子的蛋白，通过两种不同的Tat靶向肽靶向膜的质周侧。在这项工作中，这两个信号肽之间的相互关系进行了探讨。分子遗传学和生物化学方法表明，TtrB Tat信号肽的加工依赖于其伴侣蛋白TtrA的成功组装。观察到单独的TtrA或TtrB Tat靶向肽的失活对酶的组装或细胞四硫酸还原酶活性的总体影响有限。然而，这两种信号肽同时失活会完全破坏四硫酸还原酶的生理活性。这些数据表明，在酶的组装过程中，这两个信号通常都是活跃的，这意味着在信号肽之间存在一种行为准则，其中一个可以补偿另一个的不活跃。由于四硫酸还原酶很可能以多信号复合体的形式输出，这些观察结果也对细菌Tat转位酶的机制产生了影响。
Salmonella entericaserovar Typhimurium is a Gram‐negative pathogen capable of respiration with a number of terminal electron acceptors. Tetrathionate reductase is important for the infection process and is encoded by thettrBCAoperon where TtrA and TtrB are metallocofactor‐containing proteins targeted to the periplasmic side of the membrane by two different Tat targeting peptides. In this work, the inter‐relationship between these two signal peptides has been explored. Molecular genetics and biochemical approaches reveal that the processing of the TtrB Tat signal peptide is dependent on the successful assembly of its partner protein, TtrA. Inactivation of either the TtrA or the TtrB Tat targeting peptides individually was observed to have limited overall effects on assembly of the enzyme or on cellular tetrathionate reductase activity. However, inactivation of both signal peptides simultaneously was found to completely abolish physiological tetrathionate reductase activity. These data suggest both signals are normally active during assembly of the enzyme, and imply a code of conduct exists between the signal peptides where one can compensate for inactivity in the other. Since it appears likely that tetrathionate reductase presents itself for export as a multi‐signal complex, these observations also have implications for the mechanism of the bacterial Tat translocase.