Elucidating molecular level details of the plant Borate transporter structure and function.

所有的细胞都被一层由脂肪脂分子组成的膜包围着。这层膜作为一个有效的屏障，将细胞内的内容物与外界环境隔离开来。除了有限数量的分子外，脂质膜本身对所有分子都是不渗透的，然而细胞需要有一种吸收关键营养物质并清除废物的方法。通过一种被称为膜转运蛋白的特殊蛋白质系统，各种分子通过膜的输入和输出被嵌入到脂质层中。这些转运蛋白在膜的一侧与特定的底物或货物结合，经过重新配置，然后将底物释放到膜的另一侧。将关键营养物质运进和运出植物细胞的能力是植物健康生长和发育的基础。然而，由于缺乏负责矿物质摄取和分布的转运蛋白的详细信息，我们目前对植物如何吸收矿物质并精确调节其在细胞内浓度的理解非常有限。一种关键的营养物质是硼，它由根从土壤中吸收，对植物细胞壁的形成和强度起着至关重要的作用。植物能容忍的土壤溶液浓度范围很窄，介于贫壤和毒壤之间。缺硼会导致植株缩小和籽粒产量下降，这两者都对作物产量产生重大影响。硼中毒还会损害植物的生长发育。由于缺硼，中国和西非和中非的大片农业用地肥力低下，而澳大利亚、土耳其和智利的土地则受到硼中毒的影响。BOR1是一种膜转运蛋白，在植物根系向其他生长组织输送硼的过程中起作用。准确地了解硼以什么形式以及如何通过BOR1被吸收到细胞中是非常重要的。增加对BOR1运作的理解的核心是一种叫做x射线晶体学的技术，它使我们能够获得蛋白质结构中原子排列的非常详细的信息。获得转运蛋白等膜蛋白的详细结构仍然非常具有挑战性，因为必须将蛋白质从膜环境中去除到含有洗涤剂的溶液中，这样它们才能被分离和结晶。我们已经在获得BOR1的详细结构方面取得了实质性的进展，从模式植物，鼠耳衣和重要作物，水稻中获得了BOR1的良好衍射晶体。此外，我们将通过分析植物细胞和整株植物中的蛋白质来补充结构研究。我们将使用的技术使我们能够在天然环境中研究蛋白质，并评估一系列突变BOR1s的功能。结合该结构，基于植物的功能分析将为构建BOR1如何工作的独特详细图片提供机会。这应该成为未来研究的基础，以尝试培育对次优土壤硼浓度具有更好耐受性的植物。

All cells are surrounded by a membrane made up of fatty lipid molecules. This membrane acts as an effective barrier separating the contents of the cell from the external environment. The lipid membrane itself is impermeable to all but a limited number of molecules, however cells need to have a means of taking up key nutrients and removing waste products. The import and export of a wide range of molecules across the membrane is mediated via a system of specialized proteins called membrane transporters, which are embedded into the lipid layer. These transporter proteins bind a specific substrate or cargo on one side of the membrane, undergo a reconfiguration and then release the substrate on the other side of the membrane. The ability to transport key nutrients into and out of plant cells is fundamental to healthy plant growth and development. However, our current understanding of how plants take up minerals and precisely regulate their concentration inside cells is very limited due to a lack of detailed information on the transport proteins responsible for their uptake and distribution. One key nutrient is boron which is taken up from the soil by the roots and has essential roles in the formation and strength of the plant cell wall. Plants are tolerant of a very narrow range between deficient and toxic soil solution concentration. Boron deficiency causes reduced plant size and impaired seed production, both of which have a major impact on crop yield. Boron toxicity also results in compromised plant growth and development. Vast areas of agricultural land in China and West and Central Africa have poor fertility as a result of boron deficiency, while land in Australia, Turkey and Chile is affected by boron toxicity. BOR1 is a membrane transporter with roles in boron distribution from plant roots to other growing tissues. It is very important to understand precisely in what form and how boron is taken up into cells through BOR1. Central to increasing understanding of the operation of BOR1 is a technique called X-ray crystallography which allows us to obtain very detailed information on the arrangement of the atoms within a protein structure. Obtaining such detailed structures of membrane proteins such as transporters remains very challenging as it is necessary to remove the proteins from their membrane environment into a detergent containing solution so they can be isolated and crystallised. We have made substantial progress towards obtaining a detailed structure of BOR1 having obtained well diffracting crystals of BOR1 from both the model plant, mouse-ear cress, and the important crop, rice. We will additionally complement the structural studies with analysis of the protein in plant cells and whole plants. The techniques we will use allow us to study the protein in a native environment and also assess the functionality of a range of mutant BOR1s. Taken together with the structure, the plant based functional analysis will provide an opportunity to build a uniquely detailed picture of how BOR1 works. This should form the basis of future studies attempting to generate plants with improved tolerance to suboptimal soil boron concentrations.