Phosphodiesterase A1, a regulator of cellulose synthesis in Acetobacter xylinum, is a heme-based sensor
Phosphodiesterase A1, a regulator of cellulose synthesis in Acetobacter xylinum, is a heme-based sensor
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DOI：
10.1021/bi0100236
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发表时间：
2001-03-27
期刊：
影响因子：
2.9
通讯作者：
Gilles-Gonzalez, MA
中科院分区：
文献类型：
--
作者：
Chang, AL;Tuckerman, JR;Gilles-Gonzalez, MA
木醋杆菌的磷酸二酯酶A1蛋白，xPDEA 1，是细菌纤维素合成的关键调节剂。这种磷酸二酯酶将环状双（3 '-5'）二鸟苷酸（细菌纤维素合酶的变构激活剂）线性化为无效的pGpG。在这里，我们表明，AxPDEA 1含有血红素和O-2的血红素可逆结合的调节。Apo-AxPDEA 1的磷酸二酯酶活性低于holo-AxPDEA 1的2%，用氯化血红素重建后可恢复全部活性。O-2调节是由于脱氧血红素是比氧合血红素更好的激活剂。AxPDEA 1在其整个长度上与大肠杆菌直接氧传感器蛋白EcDos同源，并且仅在血红素结合PAS结构域上与FixL组氨酸激酶同源。AxPDEA 1的血红素结合结构域的性质与其他O-2响应血红素传感器的性质显著不同。AxPDEA 1自氧化的速率（半衰期> 12小时）是迄今为止对于这种类型的血红素蛋白折叠所观察到的最慢的。AxPDEA 1的O-2亲和力（Kd类似于10 μ M）与EcDos相当，但O-2结合（k（on）= 6.6 μ M（-1）s（-1））和解离（k（off）= 77 s（-1））的速率常数高2000倍。我们的研究结果说明了血红素PAS类的O-2传感器的信号转导机制的多样性，并提供了第一个例子O-2调节的第二信使。
The phosphodiesterase Al protein of Acetobacter xylinum, xPDEA1, is a key regulator of bacterial cellulose synthesis. This phosphodiesterase linearizes cyclic bis(3'-5')diguanylic acid, an allosteric activator of the bacterial cellulose synthase, to the ineffectual pGpG. Here we show that AxPDEA1 contains heme and is regulated by reversible binding of O-2 to the heme. Apo-AxPDEA1 has less than 2% of the phosphodiesterase activity of holo-AxPDEA1, and reconstitution with hemin restores full activity. O-2 regulation is due to deoxyheme being a better activator than oxyheme. AxPDEA1 is homologous to the Escherichia coli direct oxygen sensor protein, EcDos, over its entire length and is homologous to the FixL histidine kinases over only a heme-binding PAS domain. The properties of the heme-binding domain of AxPDEA1 are significantly different from those of other O-2-responsive heme-based sensors. The rate of AxPDEA1 autoxidation (half-life > 12 h) is the slowest observed so far for this type of heme protein fold. The O-2 affinity of AxPDEA1 (K-d similar to 10 muM) is comparable to that of EcDos, but the rate constants for O-2 association (k(on) = 6.6 muM(-1) s(-1)) and dissociation (k(off) = 77 s(-1)) are 2000 times higher. Our results illustrate the versality of signal transduction mechanisms for the heme-PAS class of O-2 sensors and provide the first example of O-2 regulation of a second messenger.