Controlling chromosome structure in starved bacteria

DNA可以想象成一根长长的绳子，就像绳子一样，如果不小心缠绕，DNA就会变成一团乱麻。这给生物体带来了一个问题，因为它们必须在一个小隔间（细胞）的范围内包装它们的DNA链。细胞已经进化出许多包装DNA的机制，对于更复杂的生物体（例如人类和植物），我们对这些机制的工作原理有了相当好的理解。然而，我们对细菌（如我们所熟悉的大肠杆菌和沙门氏菌）染色体折叠的了解还不够完善。在我们的工作中，我们建议确定细菌组织其DNA的机制。我们将特别关注饥饿细菌的DNA组织。这很重要，因为在饥饿的细菌中，DNA链的包装比正常情况下要紧密得多。据信，这是一种保护机制，以确保细菌在非最佳条件下生长时可能遇到的恶劣环境中DNA不会受损。例如，从受污染的肉类转移到砧板上的大肠杆菌会使用这种保护机制，直到它遇到更有利的环境（即你或我的肠道）。我们的研究将集中在一种叫做弯曲DNA结合蛋白a （CbpA）的蛋白质上，这种蛋白质与DNA结合，只有在大肠杆菌细胞饥饿时才会产生。我们的目标是确定CbpA是如何构建DNA的，DNA的哪些部分与CbpA相关，以及CbpA的活性是如何被调节的。由于与大肠杆菌相关的细菌（如沙门氏菌）也会产生CbpA，因此我们的发现应该也适用于这些生物。

DNA can be envisaged as a long piece of string and, just like string, if not carefully wound, DNA becomes a tangled mess. This presents a problem for living organisms because they have to package their string of DNA within the confines of a small compartment (the cell). Cells have evolved numerous mechanisms to package DNA and, for more complicated organisms (for example humans and plants) we have a reasonably good understanding of how these mechanisms work. However, our understanding of chromosome folding in bacteria (such as the familiar organisms E. coli and Salmonella) is less well developed. In our work we propose to identify mechanisms used by bacteria to organise their DNA. In particular we will pay attention to DNA organisation in starved bacteria. This is important because, in starved bacteria, the DNA string is packaged much more tightly than normal. It is believed that this is a protection mechanism to ensure that DNA is not damaged in the harsh environments bacteria may encounter when not growing in optimal conditions. For example, E. coli transferred to a chopping board from contaminated meat would employ such protection mechanisms until it encountered a more favourable environment (i.e. the gut of you or I). Our study will focus on a protein called Curved DNA Binding Protein A (CbpA) that binds to the DNA and is produced by E. coli cells only when they are starved. Our goals are to determine, exactly how CbpA structures DNA, which parts of the DNA are associated with CbpA, and how CbpA activity is regulated. Because CbpA is also produced by bacteria related to E. coli, such as Salmonella, our findings should also be applicable to these organisms.