The single polypeptide type I restriction enzymes - minimal multifunctional molecular motors

为了使生活更简单，人类开发了机器来承担复杂的任务。但大自然先到了那里，地球上的生命依赖于微型机器和马达的运转，这些机器和马达不是由金属齿轮和齿轮制成，而是由蛋白质制成。微型工厂正在你的身体里工作！例如，你的基因物质，DNA。有许多“分子马达酶”，其任务是识别DNA的特定部分（由称为A，G，C和T的化学碱基组成的序列），然后将化学能（以称为ATP的燃料化合物的形式）转化为机械事件。例如，我们所研究的蛋白质每次沿着DNA移动沿着数千个碱基，就像火车沿着轨道一样。一旦这些马达到达DNA中的一个确定点，它们就会停止并使用额外的酶活性切断轨道。虽然这似乎是对马达的破坏性事件，但它对细胞的健康至关重要，因为这些切割不是在宿主基因组中进行的，而是针对入侵的病毒DNA。我们希望研究的酶的一个显着特征是，所有这些复杂性都包含在一个单一的蛋白质中，有点像一个移动的电话，它也是一个相机，一个游戏机和一个MP3播放器。如何将所有的多种酶活性包含在一个蛋白质单位中，以及如何协调这些活性，以便马达可以以受控的方式沿着DNA移动？这就是我们要查明的。

To make life more straightforward, Mankind has developed machines to undertake complex tasks. But Nature got there first; life on Earth is reliant on the action of microscopic machines and motors made not from metal gears and cogs but from proteins. Miniaturised factories are working in your body right now! Take for example your genetic material, DNA. There are a great many 'molecular motor enzymes' whose task is to recognise a specific part of the DNA (a sequence made up of chemical bases called A, G, C and T) and then to convert chemical energy (in the form of a fuel compound called ATP) into mechanical events. For example, the proteins we study move along DNA many thousands of bases at a time, much like a train along a track. Once these motors reach a defined point in the DNA they stop and cut the track using an additional enzyme activity. Whilst this may seem a destructive event for the motor, it is vital to the health of the cell because these cuts are not made in the host genome but are targeted to invading viral DNA. A remarkable feature of the enzymes we wish to study is that all this complexity is contained within a single protein, a bit like a mobile phone which is also a camera, a games console and an MP3 player. How can all the multiple enzyme activities be contained in one protein unit and how are the activities coordinated so that the motor can move along DNA in a controlled fashion? This is what we intend to find out.