A HEMOPROTEIN WITH KINASE-ACTIVITY ENCODED BY THE OXYGEN SENSOR OF RHIZOBIUM-MELILOTI
A HEMOPROTEIN WITH KINASE-ACTIVITY ENCODED BY THE OXYGEN SENSOR OF RHIZOBIUM-MELILOTI
复制标题
DOI：
10.1038/350170a0
复制
发表时间：
1991-03-14
期刊：
影响因子：
64.8
通讯作者：
HELINSKI, DR
中科院分区：
文献类型：
--
作者：
GILLESGONZALEZ, MA;DITTA, GS;HELINSKI, DR
苜蓿根瘤菌固氮基因的表达受氧1，2。 当游离氧浓度降低到微需氧水平时，这些基因被诱导。 两种调节蛋白，FixL和FixJ，启动氧反应级联，编码它们的基因已被克隆2，3。 fixL产物似乎是一种跨膜传感器，其调节fixJ产物（细胞质调节因子3）的活性。 FixL和FixJ与细菌双组分调节因子4家族同源，其信号转导模式为磷酸化（综述见参考文献5-9）。 我们在这里报告的纯化FixJ和可溶性截短的FixL（FixL*），从一个单一的质粒构建体过度生产。 FixL* 催化其自身的磷酸化和ATP的γ-磷酸转移到FixJ。 所得到的FixJ-磷酸键对碱基敏感，同源系统的乙酰基磷酸也是如此。 经纯化的FixL* 的可见光谱表明，它是一种氧结合血红蛋白。 我们建议FixL通过其血红素部分感知氧，并通过控制FixJ的磷酸化来转导此信号。
THE expression of the nitrogen-fixation genes of Rhizobium meliloti is controlled by oxygen 1,2. These genes are induced when the free oxygen concentration is reduced to microaerobic levels. Two regulator proteins, FixL and FixJ, initiate the oxygen-response cascade, and the genes that encode them have been cloned 2,3. The fixL product seems to be a transmembrane sensor that modulates the activity of the fixJ product, a cytoplasmic regulator 3. FixL and FixJ are homologous to a family of bacterial two-component regulators 4, for which the mode of signal transduction is phosphorylation (reviewed in refs 5-9). We report here the purification of both FixJ and a soluble truncated FixL (FixL*), overproduced from a single plasmid construct. FixL* catalyses its own phosphorylation and the transfer of the gamma-phosphate of ATP to FixJ. The resulting FixJ-phosphate linkage is sensitive to base, as are the aspartyl phosphates of homologous systems. Visible spectra of purified FixL* show that it is an oxygen-binding haemoprotein. We propose that FixL senses oxygen through its haem moiety and transduces this signal by controlling the phosphorylation of FixJ.