Genetic Studies of ASK Gene Functions

植物的发育需要许多基因产物的协调活动，这些基因产物可以在蛋白质合成和降解水平上进行调节。许多控制花发育的调控基因编码已知的转录因子，但很少有人知道调节蛋白质水解。由美国国家科学基金会资助的研究表明，拟南芥ASK1基因调节营养和花的发育，并编码酵母和人类SKP1蛋白的同源物。SKP1是SCF泛素连接酶复合物的一个亚基，催化泛素与靶蛋白共价连接途径的第三步，介导蛋白质降解。ASK1与UFO基因相互作用，调控花发育和花基因aptala3 （AP3）和PISTILLATA （PI）的表达。工作模型是UFO和ASK1是SCF泛素连接酶的组成部分，该连接酶促进AP3和PI表达负调节因子的降解。此外，ASK1对于雄性减数分裂I中同源分离和分离至关重要。在减数分裂I中，特定的蛋白质必须在中期/后期转变时降解，以允许同源分离。因此，最简单的假设是ASK1调控这样的蛋白水解事件。拟南芥拥有至少20个SKP1同源物，命名为ask。其他ASK基因的功能尚不清楚。酵母SKP1基因对有丝分裂生长至关重要的事实表明，其他ASK基因可能具有冗余的功能，共同控制基本的细胞过程。因此，了解ASK基因的其他功能将为调控蛋白水解在发育过程中的作用提供新的见解。在本项目中，我们将进一步利用遗传和分子方法分析ASK1在调节花发育中的功能，包括UFO与ASK1在调节AP3和PI表达的背景下的相互作用。此外，ASK1在减数分裂I中控制同源分离中的作用将通过显微镜程序进行研究。此外，更多的ASK基因将通过表达研究，通过与ASK1的功能比较来表征，并且一些在花中表达的ASK基因将使用反向遗传方法进行功能测试。这些实验可能会提供关于植物生殖发育如何受基因调控的新见解，可能有益于农业和环境。在拟南芥测序刚刚完成的时候对基因功能进行研究，既及时又有益。这些实验的结果也可能为许多植物科学家以及研究非植物生物的科学家提供未来研究的起点。

Plant development requires the coordinated activity of many gene products, which can be regulated at both the levels of protein synthesis and degradation. Many regulatory genes controlling flower development encode putative transcription factors, but few are known to regulate proteolysis. Work supported by an NSF grant indicates that the Arabidopsis ASK1 gene regulates vegetative and flower development and encodes a homolog of the yeast and human SKP1 protein. SKP1 is a subunit of SCF ubiquitin ligase complexes that catalyze the third step of a pathway that covalently links ubiquitins to target proteins, mediating the degradation of proteins. ASK1 interacts with UFO genetically to regulate flower development and the expression of the floral genes APETALA3 (AP3) and PISTILLATA (PI). The working model is that UFO and ASK1 are components of a SCF ubiquitin ligase that facilitates the degradation of a negative regulator of AP3 and PI expression. Furthermore, ASK1 is essential for homolog separation and segregation during male meiosis I. In meiosis I, specific proteins must be degraded at the metaphase/anaphase transition to allow the separation of homologs. Therefore, the simplest hypothesis is that ASK1 regulates such a proteolytic event. Arabidopsis possesses at least 20 SKP1 homologs, named ASKs. The functions of the other ASK genes are not known. The fact that the yeast SKP1 gene is essential for mitotic growth suggests that other ASK gene(s) probably have redundant functions that together control essential cellular processes. Therefore, understanding other ASK gene functions should provide new insights into the role of regulated proteolysis during development. In this project, the ASK1 function in regulating flower development will be further analyzed using genetic and molecular approaches, including the interaction between UFO and ASK1 in the context of regulation of AP3 and PI expression. In addition, the role of ASK1 in controlling homolog separation in meiosis I will be investigated using microscopic procedures. Moreover, additional ASK genes will be characterized by expression studies, by functional comparison with ASK1, and some of those ASK genes expressed in the flowers will be tested for function using reverse genetic approaches. These experiments will likely provide new insights about how plant reproductive development is regulated by genes, potentially benefiting agriculture and the environment. The study of gene functions when the Arabidopsis sequencing has is just been completed is both timely and beneficial. The results from these experiments will also likely provide the starting points for future research by many in the community of plant scientists as well as those studying non-plant organisms.