Analysis of the mechanism for coupled translation in cellular and virus mRNAs

翻译是生物学中最基本的过程的最后阶段，在这个过程中，有机体的遗传物质被转化为蛋白质。在翻译过程中，核糖体(制造蛋白质的细胞机器)通过遵循一种名为信使核糖核酸的分子中的计划来制造新的蛋白质。信使核糖核酸是一种单链分子，由四种不同的成分(称为核苷酸)组成，它们的作用就像我们字母表中的字母组成一个密码。多年来，科学家们一直在研究核糖体机器在真核生物(高等生物)中的工作方式，并认为所有蛋白质都是以同样的方式制造的。病毒是一组微生物，它们感染并导致有机体中的疾病。在感染过程中，他们必须使用感染细胞的器官，包括核糖体来制造更多的新病毒。病毒被迫在被感染的细胞摧毁它之前，利用所有的细胞系统来更快地生存和繁殖。重要的是，病毒使用的所有策略都必须与细胞的工作方式兼容才能发挥作用。有趣的是，通过研究这些新的策略，科学家们已经看到，不仅病毒使用它们，而且细胞也使用它们。我们正在研究一种名为呼吸道合胞病毒(RSV)的病毒，这种病毒很可能会在儿童时期感染大多数人，并很有可能在成年后再次感染他们。RSV病毒还使用一种新的机制来表达一种名为M2-2的蛋白质。在这里，不是只用一段信使核糖核酸制造一种蛋白质，而是制造两种蛋白质。我们有兴趣弄清楚这是如何可能的。我们已经证明，为了制造第二种蛋白质：M2-2，必须制造第一种蛋白质M2-1。这意味着核糖体必须相反，因为第二种蛋白质的编码序列与第一种蛋白质的编码序列重叠。这是一个重要的发现，因为核糖体以前没有被证明具有这种能力。在这个信使核糖核酸中的重要区域已经被发现，可以制造第二种蛋白质。这些区域似乎存在于M2-1的整个编码序列中。如果我们通过引入突变或进行缺失来改变这些区域，第二种蛋白质的数量就会减少，在某些情况下是完全减少的，这表明了它们的重要性。这些部分包含大量的二级结构。二级结构出现在信使核糖核酸分子不同部分的核苷酸可以相互作用的地方，这可以被认为是将两块拼图锯组装在一起。随着更多的碎片加入，结构变得更坚固。我们将使用最新的技术来捕捉和精确定位核糖体在M2-1RNA上的位置。如果核糖体处于一个位置，而不是随机地，这将指示核糖体暂停的位置。这可能会让核糖体有效地思考并改变主意。因此，它不是做它应该做的事情，遵循停止和离开的信号，它重新启动并制造新的蛋白质，或者2)二级结构抑制核糖体运动，从而在mRNA分子上出现缺口，因此停止的核糖体也可以后移而不被阻止。我们也有兴趣找出是否有其他蛋白质协助这一过程。我们的目标是用我们的M2-1 RNA作为诱饵来钓出这些蛋白质。我们还首次发现，我们的基因组中含有执行这一过程的信使核糖核酸。我们至少有5个例子需要进一步研究，并强调了这一机制的普遍使用。

Translation is the final stage of the most fundamental process in biology in which the genetic material of the organism is turned into proteins. During the process of translation; ribosomes (which are the cellular machines that build proteins) make the new protein by following a plan written in a molecule called mRNA. mRNA is a single stranded molecule made up from 4 different components (called nucleotides) which act like letters in our alphabet to make a code. Scientists have been studying the way the ribosome machine works in eukaryotes (higher organisms) for many years and thought that all proteins are made in the same way. Viruses are a group of microscopic organisms which infect and cause diseases in organisms. During the infection process they must use the infected cell's apparatus including ribosomes to make more new viruses. Viruses have been forced to exploit all of the cell systems to survive and multiply faster before the infected cell can destroy it. Importantly, all strategies used by the virus must be compatible with the workings of the cell to function. Interestingly, by studying these new strategies Scientists have seen that not only, do the viruses use them, but the cells also do. We are studying a virus called respiratory syncytial virus (RSV) which will have likely infected most individuals a child and will have a good chance of infected them again as adults. The RSV virus also uses a novel mechanism to express a protein called M2-2. Here instead of just making one protein from a piece of mRNA two proteins are made. We are interested in working out how this is possible. We have shown that in order to make the second protein: M2-2 the first protein M2-1 must be made. This means the ribosomes must go in reverse as the coding sequence for the second protein overlaps with the coding sequence of the first. This was an important finding as ribosomes had not previously been shown to have this ability. Important regions within this mRNA have been discovered that allow the second protein to be made. These regions appear to be present throughout the coding sequence of M2-1. If we change these regions by introducing mutations or make deletions the amounts of the second protein made are reduced, in some cases completely, indicating their importance. These sections contain a lot of secondary structure. Secondary structure occurs where the nucleotides in different parts of the mRNA molecule can interact together, which can be thought of as like fitting two pieces of a jig-saw together. As more pieces are added the structure gets stronger. We are going to use the latest techniques to capture and pinpoint where the ribosome is on the M2-1 RNA. If the ribosome is in one location more than by random chance this will indicate the location where the ribosome has paused. This could 1) allow the ribosome to effectively think and change its mind. So instead of doing what it should and following a signal to stop and move away it re-starts and makes a new protein and or 2) The secondary structures inhibit ribosome movements so that gaps appear on the mRNA molecule so a ribosome stopping can also move back and not be blocked. We are also interested in finding out if other proteins assist in this process. We aim to fish out these proteins using our M2-1 RNA as bait. We have also discovered for the first time that our genome contains examples of mRNA that carry out this process. We have at least 5 examples to investigate further and highlights the universal use of this mechanism.