The bacA gene of Escherichia coli encodes an undecaprenyl pyrophosphate phosphatase activity
The bacA gene of Escherichia coli encodes an undecaprenyl pyrophosphate phosphatase activity
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DOI：
10.1074/jbc.m401701200
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发表时间：
2004-07-16
影响因子：
4.8
通讯作者：
Mengin-Lecreulx, D
中科院分区：
文献类型：
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作者：
El Ghachi, M;Bouhss, A;Mengin-Lecreulx, D
bacA 基因（其过度表达会导致杆菌肽抗性）被失活，并被证明对于大肠杆菌的生长不是必需的。较早提出，bacA 基因产物可能通过十一异丙醇磷酸化而赋予抗生素抗性（Cain, B. D.、Norton, P. J.、Eubanks, W.、Nick, H. S. 和 Allen, C. M. (1983) J. Bacteriol. 175, 3784-3789)。在目前的工作中，这种极其疏水的膜蛋白被过量生产并纯化至接近均质。对其催化特性的分析清楚地表明，纯化的 BacA 蛋白表现出十一烯基焦磷酸磷酸酶活性，但不具有十一烯醇磷酸激酶活性。这一发现与杆菌肽的作用机制完全一致，杆菌肽的作用机制在于封存 BacA 酶底物十一异戊二烯焦磷酸酯。在多拷贝表达质粒上携带 bacA 的细胞中，十一异戊二烯焦磷酸磷酸酶的水平增加了 280 倍。在 bacA 破坏突变体中，它减少了大约 75%，但并未完全消除，这表明 BacA 是主要的大肠杆菌十一异戊二烯基焦磷酸磷酸酶，但应该存在其他表现出这种活性的蛋白质，以解释突变菌株的残余活性和活力。这是迄今为止确定的第一个编码十一异戊二烯焦磷酸磷酸酶的基因。考虑到其新发现的功能，我们建议将 bacA 基因重命名为 uppP。
The bacA gene, the overexpression of which results in bacitracin resistance, was inactivated and shown to be non-essential for growth of Escherichia coli. It was proposed earlier that the bacA gene product may confer resistance to the antibiotic by phosphorylation of undecaprenol (Cain, B. D., Norton, P. J., Eubanks, W., Nick, H. S., and Allen, C. M. (1983) J. Bacteriol. 175, 3784-3789). In the present work, this extremely hydrophobic membrane protein was overproduced and purified to near homogeneity. The analysis of its catalytic properties clearly demonstrated that the purified BacA protein exhibited undecaprenyl pyrophosphate phosphatase activity but not undecaprenol phosphokinase activity. This finding was perfectly consistent with the mechanism of action of bacitracin that consists in the sequestration of undecaprenyl pyrophosphate, the BacA enzyme substrate. The level of undecaprenyl pyrophosphate phosphatase was increased by 280-fold in cells carrying bacA on a multicopy expression plasmid. It was decreased by similar to75% but was not completely abolished in a bacA disruption mutant, suggesting that BacA is the main E. coli undecaprenyl pyrophosphate phosphatase but that other protein(s) exhibiting such an activity should exist to account for the residual activity and viability of the mutant strain. This is the first gene encoding undecaprenyl pyrophosphate phosphatase identified to date. Considering its newly identified function, we propose to rename the bacA gene uppP.