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

在这个由化学部生命过程化学计划资助的职业奖项中，Tatana Igumenova博士描述了一个专注于铅(铅)生物化学的综合研究和教育计划。尽管铅(II)暴露对人类的影响是众所周知的，但人们对铅(II)作用的分子机制了解很少。Igumenova Pi博士将使用协同结构和功能方法对铅(II)-蛋白质相互作用进行第一次深入的系统研究。重点放在一类被称为保守同源2或C2结构域的外周膜蛋白上。这个蛋白质系统使PI能够处理铅(II)作用的一个未被探索的方面：它如何调节蛋白质-膜相互作用。这些研究中选择的C2结构域来自三个亲本蛋白，它们是铅(II)的分子靶标。这些蛋白质具有不同的结构和功能，如信号转导和膜转运。伊古梅诺娃博士已经组装了一套生物物理技术工具包，将能够在没有和存在类脂膜的情况下表征铅(II)-蛋白质的相互作用。这些研究的结果将报道由铅(II)结合带来的C2结构域化学环境的变化如何影响下游反应，即C2与脂膜的结合。这些结果有可能改变传统的观点，即铅(II)作为一种配体，其作用仅限于形成高亲和力的蛋白质络合物作为功能钙替代的配体。得到的数据将使PI能够识别膜结合和无膜C2结构域中配位几何和铅(II)亲和力的预测因子。这反过来将有助于确定其他潜在的铅(II)目标。铅(铅)是一种重金属，由于人类活动，其丰度比其自然水平高出1000倍。环境中最普遍的铅形式是铅(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情况下结合钙离子的蛋白质。铅(II)离子成功地与钙离子竞争，并以高亲和力与这些蛋白质结合，这些蛋白质被称为铅(II)的分子靶标。Igumenova博士的目标是确定这些蛋白质的特征，使它们与铅(II)结合得比钙离子更紧密，并了解铅(II)对蛋白质功能的影响。拟议工作的一个更广泛的影响是，来自代表性不足群体的学生进入研究生课程。伊古梅诺娃博士将提供为期10周的暑期研究实习机会，她在NSF赞助的路易斯·斯托克斯少数族裔参与联盟(LSAMP)和本科生研究经验(REU)项目中担任教师导师，从而促进了招聘工作。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核磁共振仪器)和REU附属计划来完成。作为一项推广活动，伊古梅诺娃博士的实验室将为iPhone/iPad/iPod移动平台开发一个教育网络应用程序(APP)：“铅(铅)：有毒化学物质在起作用”。其目的是提高公众对Pb2+对社会的有害影响的认识，从环境中铅(II)的古代和现代来源到伊古梅诺娃博士的研究活动产生的特定的铅(II)络合分子结构。对社会的好处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.