Structure/function studies of a cyclomodulin

蛋白质是由基因编码的生物分子，是生命的分子机器。蛋白质形成复杂的三维结构，经常决定它们的功能。蛋白质的功能通常依赖于与另一个分子的相互作用，这种相互作用导致效应。本提案中描述的实验旨在研究病原菌蛋白质的结构和功能，该蛋白质能够在感染期间改变宿主细胞的特性。具体来说，这种称为“Cif”的蛋白质会干扰宿主细胞周期（生长和分裂过程）的进展，使其不可逆地停止。虽然目前还不清楚为什么，但这可能对入侵的细菌有一些好处。研究这样的蛋白质对于理解宿主-病原体相互作用（疾病的分子原因）和宿主细胞过程本身都很重要。例如，失调的细胞周期通常与癌症的发展有关，而调节细胞周期的蛋白质是制药行业最有针对性的分子之一。Cif实际上如何在宿主细胞中发挥作用目前尚不清楚。确定这种蛋白质如何发挥功能的一种有效方法是观察其结构。这可以使用称为X射线晶体学的技术可视化，然后使用计算机图形重建模型。一旦结构已知，就可以设计蛋白质的改变以进一步研究宿主细胞中的蛋白质功能。对于理解Cif功能同样重要的是识别宿主细胞内蛋白质的分子靶标（最有可能是其他蛋白质），表征相互作用（它们相互结合的强度如何？），并最终决定分子的结构。这将产生细菌蛋白与宿主细胞蛋白相互作用的图像，以及负责转导最终导致宿主细胞周期停滞的效应的复合物。了解Cif的这些相互作用的性质对于开发针对宿主-病原体相互作用和致癌作用的新型疗法具有长期应用。

Proteins are a biological molecules encoded by a gene, and they are the molecular machines of life. Proteins form a complex 3-dimensional structure that frequently determines their function. A protein's function is usually dependent on interaction with another molecule and this interaction leads to an effect. The experiments described in this proposal aim to investigate the structure and function of a protein from pathogenic bacteria that is able to change the properties of the host cell during infection. Specifically this protein, called 'Cif' interferes with progression of the host cell cycle (process of growth and division), irreversibly stopping it in its tracks. Although it is not currently understood why, this presumably has some benefit for the invading bacteria. Studying proteins such as this is important for both understanding host-pathogen interactions (the molecular causes of disease) and the host cell processes themselves. For instance, a deregulated cell cycle is often linked to development of cancer, and proteins that regulate the cell cycle are one of the most targeted set of molecules by the pharmaceutical industry. How Cif actually brings about its effect in host cells is not currently understood. One powerful approach to determining how this protein functions is to look at its structure. This can be visualised using a technique called X-ray crystallography followed by reconstruction of a model using computer graphics. Once the structure is known alterations to the protein can be designed to further investigate protein function in host cells. Also important for understanding Cif function is identifying the protein's molecular targets within host cells (most likely other proteins), characterising the interaction (how strongly do they bind to each other?), and ultimately determining the structure of molecules together. This would generate a picture of a bacterial protein interacting with a host cell protein, and a complex responsible for transducing an effect ultimately leading to host cell cycle arrest. Understanding the nature of these interactions for Cif has long-term applications for development of novel therapeutics targeting host-pathogen interactions and also carcinogenesis.