CAREER: Biological chemistry of Pb2+ revealed through Pb2+ mediated protein-membrane interactions

在这个由化学部生命过程计划化学资助的职业奖中，Tatyana Igumenova博士描述了一个专注于铅（Pb）生物化学的综合研究和教育计划。 尽管铅（II）暴露对人类的影响众所周知，但铅（II）作用的分子机制知之甚少。 Igumenova PI博士将使用协同结构和功能方法对Pb（II）-蛋白质相互作用进行首次深入系统的研究。 重点是一类称为保守同源2或C2结构域的外周膜蛋白。 这种蛋白质系统使PI能够解决Pb（II）作用的一个未探索的方面：它如何介导蛋白质-膜相互作用。 选择用于这些研究的C2结构域是从三个亲本蛋白质，是Pb（II）的分子靶标。 这些蛋白质具有不同的结构和功能，如信号转导和膜运输。 Igumenova博士已经组装了一个生物物理技术工具包，这将使Pb（II）-蛋白质相互作用的表征在脂质膜的存在和不存在。 拟议的研究结果将报告如何在C2域的化学环境的变化，所带来的Pb（II）结合，影响下游反应，这是协会的C2与脂膜。 这些结果有可能改变传统的观点Pb（II）作为配体，其作用仅限于形成高亲和力的蛋白质复合物的配体，作为一个功能性的Ca2+替代品。 所获得的数据将使PI确定的预测配位几何形状和Pb（II）的亲和力在膜结合和膜自由C2域。 这反过来又将有助于确定其他潜在的铅（II）目标。铅（Pb）是一种重金属，由于人类活动，其富集程度超过其自然水平1000倍。 铅在环境中最普遍的形式是Pb（II），它与细胞中的生物分子相互作用。 这些生物分子中的许多是在正常条件下结合钙离子的蛋白质。 铅（II）离子成功地与钙离子竞争，并以高亲和力结合到这些蛋白质上，这些蛋白质被称为铅（II）的分子靶点。 Igumenova博士的目标是确定这些蛋白质的特征，使它们比钙离子更紧密地结合Pb（II），并了解Pb（II）对蛋白质功能的影响。 拟议工作的更广泛影响之一是来自代表性不足群体的学生进入研究生课程。 Igumenova将提供为期十周的暑期研究实习，她作为NSF赞助的路易斯·斯托克斯少数民族参与联盟（LSAMP）和本科生研究经验（REU）计划的教师导师的活动促进了招聘。 学生的专业发展和指导将通过研究活动，使用高端研究仪器（800 MHz NMR仪器）和REU附属计划来完成。 作为一项推广活动，Igumenova博士的实验室将为iPhone/iPad/iPod移动的平台开发一个教育网络应用程序："铅（Pb）：行动中的有毒化学物质"。 目的是提高公众对Pb2+对社会的有害影响的认识，从环境中Pb（II）的古代和现代来源到由于Igumenova博士的研究活动而产生的特定Pb（II）络合分子结构。 对社会的好处将是提高公众对铅暴露没有安全水平这一事实的认识。

In this CAREER award, funded by the Chemistry of Life Processes Program in the Chemistry Division, Dr. Tatyana Igumenova describes an integrated research and educational program focused on the biological chemistry of lead (Pb). Despite the well-known effect of Pb(II) exposure on humans, the molecular mechanism of Pb(II) action is poorly understood. Dr. Igumenova PI will use a synergistic structural and functional approach to conduct the first in-depth systematic investigation of Pb(II)-protein interactions. The focus is on a class of peripheral membrane proteins called conserved homology 2, or C2, domains. This protein system enables the PI to tackle an unexplored aspect of Pb(II) action: how it mediates the protein-membrane interactions. The C2 domains selected for these studies are from three parent proteins that are molecular targets of Pb(II). These proteins have different structures and functions, such as signal transduction and membrane trafficking. Dr. Igumenova has assembled a toolkit of biophysical techniques that will enable characterization of Pb(II)-protein interactions in the absence and presence of lipid membranes. The results of the proposed studies will report on how the change in the chemical environment of C2 domains, brought about by Pb(II) binding, affects the downstream reaction, which is the association of C2 with lipid membranes. These results have a potential to transform the conventional view of Pb(II) as a ligand whose action is limited to the formation of high-affinity protein complexes to a ligand that serves as a functional Ca2+ surrogate. The obtained data will enable the PI to identify the predictors of coordination geometries and Pb(II) affinities in membrane-bound and membrane-free C2 domains. This, in turn, will facilitate the identification of other potential Pb(II) targets.Lead (Pb) is a heavy metal that became enriched 1000-fold above its natural level due to human activity. The most prevalent form of lead in the environment, Pb(II), interacts with biological molecules in the cell. Many of these biological molecules are proteins that bind calcium ion under normal conditions. Lead(II) ion successfully competes with calcium ion and binds to these proteins - referred to as molecular targets of Pb(II) - with high affinity. Dr. Igumenova's objective is to determine the features of these proteins that make them bind Pb(II) more tightly than calcium ion and understand the effect of Pb(II) on protein function. One of the broader impacts of the proposed work is entry of students from under-represented groups into graduate programs. Dr. Igumenova will offer ten-week summer research internships, with recruitment facilitated by her activities as a faculty mentor in the NSF-sponsored Louis Stokes Alliance for Minority Participation (LSAMP) and Research Experience for Undergraduates (REU) programs. Professional development and mentoring of the student will be accomplished through research activities, the use of high-end research instrumentation (an 800 MHz NMR instrument), and REU-affiliated programs. As an outreach activity, Dr. Igumenova's laboratory will develop an educational web application (app): "Lead (Pb): the toxic chemistry in action" for the iPhone/iPad/iPod mobile platforms. The objective is to enhance public knowledge of the harmful effects of Pb2+ on the society, from the ancient and modern sources of Pb(II) in the environment to specific Pb(II)-complexed molecular structures generated as a result of Dr. Igumenova's research activities. The benefit for society will be an increase in public awareness to the fact that there is no safe level of Pb exposure.