Merrick Mike
Department of Molecular Microbiology, John Innes Centre Norwich, UK.
Front Microbiol. 2015 Jan 6;5:763. doi: 10.3389/fmicb.2014.00763. eCollection 2014.
The PII proteins constitute one of the most widely distributed families of signal transduction proteins in nature. They are pivotal players in the control of nitrogen metabolism in bacteria and archaea, and are also found in the plastids of plants. Quite remarkably PII proteins control the activities of a diverse range of enzymes, transcription factors and membrane transport proteins, and in all known cases they achieve their regulatory effect by direct interaction with their target. PII proteins in the Proteobacteria and the Actinobacteria are subject to post-translational modification by uridylylation or adenylylation respectively, whilst in some Cyanobacteria they can be modified by phosphorylation. In all these cases the protein's modification state is influenced by the cellular nitrogen status and is thought to regulate its activity. However, in many organisms there is no evidence for modification of PII proteins and indeed the ability of these proteins to respond to the cellular nitrogen status is fundamentally independent of post-translational modification. In this review we explore the role of post-translational modification in PII proteins in the light of recent studies.
PII蛋白是自然界中分布最广泛的信号转导蛋白家族之一。它们是细菌和古细菌中氮代谢控制的关键参与者，在植物的质体中也有发现。非常值得注意的是，PII蛋白控制着多种酶、转录因子和膜转运蛋白的活性，在所有已知情况下，它们都通过与靶标直接相互作用来实现其调节作用。变形菌门和放线菌门中的PII蛋白分别通过尿苷酸化或腺苷酸化进行翻译后修饰，而在一些蓝细菌中，它们可以通过磷酸化进行修饰。在所有这些情况下，蛋白质的修饰状态受细胞氮状态的影响，并被认为调节其活性。然而，在许多生物体中，没有证据表明PII蛋白会发生修饰，实际上这些蛋白对细胞氮状态作出反应的能力基本上与翻译后修饰无关。在这篇综述中，我们根据最近的研究探讨翻译后修饰在PII蛋白中的作用。
