Biochemistry, biology and diversity of Fic domains

项目摘要 各种细胞过程通常被颠覆以鼓励癌细胞的增殖， 其中之一是发生在内质网(ER)中的未折叠蛋白反应(UPR)。 重要的是，UPR与炎症或神经元健康之间也有很强的联系。 许多神经退行性疾病和老年病都与UPR有关。我们有 最近发现了一种新的BiP调控形式，即由Fic蛋白进行的AMP化。我们注意到该图 将一磷酸腺苷(AMP)分子添加到Bip的ATP结合位点附近的苏氨酸 在正常生长条件下。这种修饰迅速被同一种酶Fic在 多种内质网应激诱导条件。我们最近已经表明，FIC对BIP的调节是 对于维持神经元的动态平衡是必不可少的。自从我们发现了FIC结构域， AMP化，细菌Fic结构域执行的其他不同的活性已经被确定。这些 研究表明，Fic结构域在利用不同底物方面具有分子可塑性。 尽管有这些研究，但仍有许多不同的Fic蛋白有待鉴定，两者都是 催化活性、生物功能和分子靶标。我们提出了三个项目，将进一步 我们对Fic酶的生物学及其在体外和体内使用的化学物质的理解。 首先，当ER受到压力时，FIC从AMPylator变成DeAMPylator，而这一点的关键 监管机构正在打破FIC活跃地点的盐桥。我们想要了解生物化学 调节这个开关。其次，我们对果蝇遗传学的研究表明，Fic是 神经元的可塑性。因此，我们有兴趣了解FIC在哺乳动物中所起的作用 使用转基因小鼠进行生物学研究。第三，还有许多不同的Fic蛋白有待研究 在催化活性、生物功能和分子靶标方面都进行了表征。我们计划 研究这些孤立的Fic结构域，并鉴定它们的生物活性和底物。

Project Summary A variety of cellular processes are commonly subverted to encourage the proliferation of cancer cells, one of which is the unfolded protein response (UPR) that occurs in the endoplasmic reticulum (ER). Importantly, there is also a strong connection between UPR and inflammation or neuronal health. Many neurodegenerative diseases and diseases of aging have connections to the UPR. We have recently discovered a new form of BiP regulation, AMPylation by the protein Fic. We observe that Fic adds an adenosine monophosphate (AMP) molecule to a threonine near the ATP binding site of BiP during normal growth conditions. This modification rapidly is removed by the same enzyme Fic under multiple ER stress-inducing conditions. We recently have shown that the regulation of BiP by Fic is essential for maintaining neuronal homeostasis. Since our discovery of Fic domains that mediate AMPylation, other diverse activities performed by bacterial Fic domains have been identified. These studies have revealed the molecular plasticity of Fic domains in its ability to utilize diverse substrates. Despite these studies, there are many different Fic proteins that remain to be characterized, both in catalytic activity, biological function, and molecular targets. We propose three projects that will further our understanding of the biology of Fic enzymes and the chemistry they use, both in vitro and in vivo. First, when the ER is stressed, Fic changes from an AMPylator to a deAMPylator, and the key to this regulation is breaking a salt bridge in Fic's active site. We want to understand the biochemistry regulating this switch. Second, our studies with Drosophila genetics show that Fic is required for neuronal plasticity. We are therefore interested in understanding what role Fic plays in mammalian biology using transgenic mice. Third, there are many different Fic proteins that remain to be characterized, both in catalytic activity, biological function, and molecular targets. We plan to investigate these orphan Fic domains and identify their biological activities and substrates.