Regulation of dictyostelium type 1 myosins

运动是活细胞的基本特性之一。我们正在研究一种阿米巴，盘基网托盘基线虫，它是一个很好的模型系统，可以用来研究细胞运动的分子机制。网柄蠕虫在表面爬行，伸展和收缩突起，改变形状，吞噬其他微生物，并分裂成两半。所有这些类型的运动都依赖于肌球蛋白马达蛋白与由肌动蛋白组成的细丝网络的相互作用。肌球蛋白具有将化学能转化为沿肌动蛋白细丝运动的独特能力。大多数细胞含有几种不同类型的肌球蛋白，所有肌球蛋白都由一个大的亚基或重链组成，该大的亚基或重链与一个或多个较小的亚基或多个轻链结合。轻链在调节肌球蛋白的活性方面起着关键作用，但令人惊讶的是，对于大多数肌球蛋白来说，轻链亚基的身份仍然未知。在过去的几年里，我们在鉴定网柄菌肌球蛋白轻链亚基方面取得了相当大的进展。出乎意料的是，我们发现大多数网柄菌肌球蛋白都有独特的轻链。我们还发现了另一种调节肌球蛋白的机制，它涉及一种名为pakB的蛋白激酶，它可以将磷酸连接到肌球蛋白的重链上。在拟议的研究中，我们将研究肌球蛋白重链和轻链是如何相互识别的，以及轻链的选择如何影响肌球蛋白在细胞中的功能。我们还将开展研究，以更好地了解pakB的监管。总之，这些研究将为细胞中肌球蛋白马达蛋白的调控提供重要的新见解。在过去的五年里，三名硕士学生和三名博士生接受了这个项目的培训。接受该项目培训的新生将获得一系列技术方面的经验，包括分子生物学、蛋白质生物化学、结构分析和细胞生物学，这些技术是学术研究人员以及生物技术和制药行业所需要的。

Movement is one of the fundamental properties of living cells. We are studying an amoeba, Dictyostelium discoideum, that serves as an excellent model system for investigating the molecular mechanisms that underlie cell motility. Dictyostelium amoeba crawl over surfaces, extend and retract protrusions, change shape, engulf other microorganisms and divide by splitting into two. All of these types of movement depend on the interaction of a myosin motor protein with a network of filaments made up of the protein actin. Myosins have the unique ability to convert chemical energy into movement along actin filaments. Most cells contain several different types of myosin, all of which consist of a large subunit, or heavy chain, that is bound to one or more smaller subunits, or more light chains. The light chains play a critical role in regulating the activity of myosin, but surprisingly, for most myosins the identity of the light chain subunits remain unknown. Over the last several years we have made considerable progress in identifying the light chain subunits of the Dictyostelium myosins. Unexpectedly, we have discovered that most Dictyostelium myosins have unique light chains. We have also discovered another mechanism that regulates myosin, which involves a protein kinase, termed PakB, that can attach a phosphate to the heavy chain of the myosin. In the proposed research we will examine how the myosin heavy chains and light chains recognize each other and how the choice of the light chain effects the function of myosin in the cell. We also will carry out studies to better understand the regulation of PakB. Together, these studies will provide important new insights into the regulation of myosin motor proteins in cells. Over the last five years three MSc students and three PhD students have been trained on this project. New students trained on this project will gain experience in a range of techniques, including molecular biology, protein biochemistry, structural analysis and cell biology, that are in demand by academic researchers and by biotechnology and pharmaceutical industries.