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首页> 外文期刊>Journal of bacteriology >Manganese, an Essential Trace Element for N2 Fixation by Rhodospirillum rubrum and Rhodopseudomonas capsulata: Role in Nitrogenase Regulation
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Manganese, an Essential Trace Element for N2 Fixation by Rhodospirillum rubrum and Rhodopseudomonas capsulata: Role in Nitrogenase Regulation

机译：锰，由红红螺旋藻和荚膜红假单胞菌固氮的必需微量元素：在固氮酶调节中的作用

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Nitrogenase (N2ase) from the photosynthetic bacterium Rhodospirillum rubrum can exist in two forms, an unregulated form (N2ase A) and a regulatory form (N2ase R), the latter being identified in vitro by its need for activation by a Mn2+-dependent N2ase activating system. The physiological significance of this Mn2+-dependent N2ase activating system was suggested here by observations that growth of R. rubrum and Rhodopseudomonas capsulata on N2 gas (a condition that produces active N2ase R) required Mn2+, but growth on ammonia or glutamate did not. Manganese could not be shown to be required for the biosynthesis of either nitrogenase or glutamine synthetase or for glutamine synthetase turnover, but it was required for the in vitro activation of N2ases from N2 and glutamate-grown R. rubrum and R. capsulata cells. Chromatium N2ase, in contrast, was always fully active and did not require Mn2+ activation, suggesting that only the purple nonsulfur bacteria are capable of controlling their N2ase activity by this new type of regulatory system. Although R. rubrum could not substitute Fe2+ for Mn2+ in the in vivo N2 fixation process, Fe2+ and, to a lesser extent, Co2+ could substitute for Mn2+ in the in vitro activation of N2ase. Electron paramagnetic resonance spectroscopy of buffer-washed R. rubrum chromatophores showed lines characteristic of Mn2+. Removal of the Mn2+-dependent N2ase activating factor by a salt wash of the chromatophores removed 90% of the Mn2+, which suggested a specific coupling of this metal to the activating factor. The data presented here all indicate that Mn2+ plays an important physiological role in regulating the N2 fixation process by these photosynthetic bacteria.
机译：来自光合细菌 Rhodospirillum rubrum 的固氮酶（N 2 ase）可以以两种形式存在，一种不受调控的形式（N 2 ase A）和一种调节形式（N 2 ase R），后者是通过需要依赖Mn 2 + 依赖的N 2 激活而在体外鉴定的酶激活系统。观察到 R的生长，表明了该依赖于Mn 2 + 的N 2 酶激活系统的生理学意义。 N 2 气体（产生活性N 2 酶R的条件）上的rumrum 和荚膜红假单胞菌需要Mn 2 + ，但氨水或谷氨酸盐的生长却没有。不能证明锰是固氮酶或谷氨酰胺合成酶的生物合成或谷氨酰胺合成酶转换所必需的，但它是体外活化N 2 <的N 2 酶所必需的/ sub>和谷氨酸生长的 R。 rubrum 和 R。荚膜细胞相比之下， Chromatium N 2 酶始终完全活跃，不需要Mn 2 + 活化，这表明只有紫色的非硫细菌是能够通过这种新型的调控系统控制其N 2 酶的活性。虽然 R。 rubrum 在体内N 2 固定过程中不能用Fe 2 + 替代Mn 2 + ，Fe 2 + ，在较小程度上，Co 2 + 可以在体外激活N 2 上代替Mn 2 + ase。缓冲液洗涤的 R的电子顺磁共振光谱。 rubrum 色谱显示出Mn 2 + 的特征。盐洗去掉Mn 2 + 依赖性N 2 酶激活因子后，去除了90％的Mn 2 + ，这暗示了这种金属与活化因子的特定偶联。此处提供的数据均表明Mn 2 + 在调节这些光合细菌对N 2 的固定过程中起着重要的生理作用。

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