Functional Characterization of the Sucrose Binding Protein

*9514410 GRAMES调节碳分配到各种器官和发育中的种子的过程直接影响植物的生长、发育和生产力。在几乎所有的植物中，最重要的运输养分是蔗糖，因此，了解蔗糖运输的分子生物学、生化和生理学是植物生物学的中心问题。蔗糖是一种化学惰性碳水化合物，是在光合作用活跃的叶片的细胞质中合成的，在被称为“韧皮部加载”的过程中，以浓度梯度的方式活跃地加载到韧皮部中，以便进行长途运输。蔗糖在运输到下沉组织后，如发育中的种子，从韧皮部卸载到质外体空间，在许多植物中，蔗糖穿过质膜运输到下沉组织细胞。已知蔗糖在质膜上的移动是一个很好的调节过程，始于汇聚组织细胞对蔗糖的吸收。在NSF的资助下，Grimes博士和他的同事们已经证明，这种对蔗糖的吸收可能是由蔗糖结合蛋白(SBP)介导的。本研究的目的是阐明植物蔗糖运输的基本生物化学，并确定SBP在蔗糖吸收中的机制作用。这项工作具有重要意义，因为它将为我们提供一个新的膜运输过程的洞察力，并有助于我们理解植物如何利用光合作用产物来促进它们的生长和发育。***

*** 9514410 Grimes The processes that regulate carbon allocation to various organs and the developing seed directly impact plant growth, development, and productivity. In nearly all plants, the most important translocated nutrient is sucrose and, thus, understanding the molecular biology, biochemistry, and physiology of sucrose transport is a central problem in plant biology. Sucrose, a chemically inert carbohydrate, is synthesized in the cytosol of photosynthetically active leaves and, in a process termed "phloem loading," is actively loaded into the phloem against a concentration gradient for long distance transport. After transport to sink tissues, such as the developing seed, sucrose is unloaded from the phloem into the apoplastic space and, in many plant species, transported across the plasma membrane into the sink tissue cells. It has been known that sucrose movement across the plasm membrane is a well regulated process and begins with uptake of sucrose by the sink tissue cells. With funding from the NSF, Dr. Grimes and his colleagues have demonstrated that this uptake of sucrose may be mediated by the sucrose binding protein (SBP). The intent of this research is to elucidate the basic biochemistry of sucrose transport in plants and define the mechanistic role of the SBP in sucrose uptake. This work is significant in that it will provide insight into a novel membrane transport process, and contribute to our understanding of how plants make use of photosynthetic products for their growth and development. ***