CAREER: The protein-mineral bond

力量是看不见的，但在任何地方都能感觉到它们的存在。对于像人类这样的大型生物来说，地心引力对我们的生活起着决定性的影响。对于细菌等较小的生物来说，重力是一种微不足道的力量。相反，分子间的力量控制着微生物的世界。这份职业计划将探索一系列空间尺度上的力，从多肽-矿物界面的结合力到人与天体之间存在的引力。这项提案的研究部分将集中于测量可能的矿物质结合蛋白和多肽的能量景观。这将通过使用原子力显微镜(AFM)来检查转换力(即破碎力)与施加到特定蛋白质-矿物质对的力的速率之间的关系来实现。蛋白质样本将包括来自金属还原细菌Shewanella onedensis的假定矿物结合蛋白(MtrC和OMCA)，以及表达具有假定矿物结合基序的多肽的噬菌体，以及掺杂矿物结合蛋白的人造膜。矿物样品将包括赤铁矿(Fe2O3)、针铁矿(FeOOH)、软锰矿(MnO2)和锰矿(MnOOH)的结晶薄膜。分子模拟将被用来确定假定的矿物结合基序的理论稳定性以及特定多肽对特定矿物相的亲和力。这项拟议的工作将(1)确定每个多肽-矿物对(例如，MtrC-赤铁矿)的基本动力学和热力学性质，如解离自由能、解离速率和到过渡势垒的距离；(2)基于基本结合元件定义每个蛋白质(MtrC和OMCA)的矿物底物(S)；(3)定义MtrC和OMCA初级序列中矿物结合结构域的边界；(4)确定MtrC或OMCA中可能的矿物结合结构域是否类似于由噬菌体进化的矿物结合基序；(5)将测量的动力学/热力学数据与多肽-矿物键的分子模拟预测值进行比较；(6)使用MtrC和OMCA的结合力签名创建亲和图，显示特定蛋白质在活细胞表面的位置。更广泛的影响地质/地球科学的一大优势是这一学科所涵盖的时间和空间的广度。这项提案描述了一项教育推广计划，向从小学到研究生的学生传授从纳米尺度(例如，分子间力)到无限大(例如，引力)存在的力。参加了拟议的外展计划的学生将对我们宇宙中的基本力量及其对生物有机体的影响有更强烈的认识。这项提案的教育宣传部分将创建一个关于“自然界的力量”的系列讲座和一个与细菌地下运输有关的补充实验室。这个讲座和实验将每年向大约1500名本科生讲授，这些本科生参加了一个名为地球的课程。参加地球班的教育学专业的学生将反过来协助PI在当地一所公立学校为小学生举办为期一周的夏令营。这个训练营将包括与微生物学、聚合物和作用力有关的动手实验。在夏令营的最后一天，学生们将教老师，即孩子们将指导父母/老师完成本周早些时候孩子们所做的相同的实验。这项教育推广计划还包括一项拟议中的科学“占星术测试”，这项测试将在大学校报上进行，大约有5万名学生可以参加。这项测试在引力和天体对我们生活产生影响的观念之间得出了一个新的对比。最后，该奖项将资助三名学生(两名本科生和一名研究生)，他们将参与上述拟议的研究项目。

EAR-0745808LOWER, Stephen K.Forces are invisible yet their presence can be felt anywhere. For large organisms, like humans, the force of gravity exerts a controlling influence on our lives. For smaller organisms, like bacteria, gravity is a trivial force. Rather, intermolecular forces control the world of microbes. This CAREER proposal will explore forces at a range of spatial scales, from binding forces at the peptide-mineral interface to the gravitational attraction that exists between humans and celestial objects. The research portion of this proposal will focus on measuring the energy landscapes of putative mineral-binding proteins and peptides. This will be accomplished by using atomic force microscopy (AFM) to examine the relationship between the transition force (i.e. rupture force) and the rate at which the force is applied to a particular protein-mineral pair. Proteins specimens will include putative mineral-binding proteins (MtrC and OmcA) from the metal reducing bacterium Shewanella oneidensis, as well as phage that express peptides with putative mineral-binding motifs, and artificial membranes doped with mineral-binding proteins. Mineral specimens will include crystalline, thin films of hematite (Fe2O3), goethite (FeOOH), pyrolusite (MnO2), and manganite (MnOOH). Molecular simulations will be used to determine the theoretical stability of putative mineral-binding motifs and the affinity of particular peptides towards specific mineral phases. This proposed work will (1) determine fundamental kinetic and thermodynamic properties such as, the free energy of dissociation, the rate of dissociation, and the distance to the transition barrier, for each peptide-mineral pair (e.g., MtrC-hematite); (2) define the mineral substrate(s) for each protein (MtrC and OmcA) based on fundamental binding elements; (3) define the boundaries of mineral-binding domains within the primary sequences of MtrC and OmcA; (4) determine whether putative mineral-binding domains within MtrC or OmcA are similar or dissimilar to mineral-binding motifs evolved by phage; (5) compare the measured kinetic/thermodynamic data to values predicted by molecular simulations of peptide-mineral bonds; (6) use the binding force-signature of MtrC and OmcA to create affinity maps that show the location of specific proteins on the surface of living cells. Broader impact One of the great strengths of Geological/Earth Science is the breadth of time and space that are encompassed by this discipline. This proposal describes an educational outreach program that teaches students from elementary to graduate school about forces that exist from the nanometer length-scale (e.g., intermolecular forces) to the infinite (e.g., the gravitational force). Students who participate in the proposed outreach programs will come away with a much stronger appreciation of the fundamental forces within our universe and their impact on living organisms. The educational outreach portion of this proposal will create a lecture series on "Forces in Natur" and a complementary lab related to subsurface transport of bacteria. This lecture and lab will be taught every year to about 1500 undergraduate students enrolled in a class called Planet Earth. Education majors enrolled in the Planet Earth class will, in turn, assist the PI as he conducts a one-week summer camp for elementary school students at one of the local, pubic schools. This camp will consist of hands-on experiments related to microbiology, polymers, and forces. On the final day of camp, the students will teach the "teachers", that is, the children will guide the parents/teachers through the same experiments the children performed earlier in the week. The education outreach plan also includes a proposed scientific "test of astrology" that will be run in the university newspaper, which is available to about 50,000 students. This test draws a novel comparison between the gravitational force and the idea that celestial objects exert a force of influence on our lives. Finally, this award will fund three students (two undergraduate and one graduate student) who will participate in the proposed research project described above.