Collaborative Research - Protein Mediated Magnetite Biomineralization

在新兴的技术和医学领域（例如，高密度数据存储、靶向药物递送、组织再生支架）。 这些应用中的许多应用的“理想”颗粒是纳米级磁体，其具有限定的形状和形态、窄的尺寸分布、高结晶度和受控的磁性方向。 趋磁细菌（MTB）具有合成符合所有这些标准的矿物磁铁矿（Fe 3 O 4）晶体的先天能力。 在这个提议中，研究人员将研究MTB对磁铁矿的蛋白质定向结晶作用。MTB对它们的纳米磁性晶体的大小、成分和形态进行严格的遗传控制。 研究人员将检查所谓的Mms蛋白（Mms-5，6，12，13;或类似MamC的同系物），以确定指导Fe 3 O 4成核和生长的关键催化结构域。 体内生物矿化实验将使用野生型菌株（例如，Magnetocellum magneticum）以及该项目期间产生的突变菌株。 将使用重组蛋白或模拟关键基序的肽进行体外结晶实验。 将使用电子显微镜、原子力显微镜、共聚焦激光扫描显微镜和磁力计来表征体内与体外矿物质产品的结构和磁性。 这些蛋白质或肽催化新的矿物产品将进一步研究使用分子动力学模拟在硅片。 从这些研究中获得的知识将允许制造纳米尺度的单畴磁性晶体，其被设计为引起特定的磁响应。 该项目还包括一个面向初中和高中学生和教师的教育推广部分。 教师每年将花费3-4周的时间与PI一起学习如何从环境样本中收集和分离MTB，以及使用各种形式的光学和电子显微镜表征MTB。 根据这些经验，教师将设计实验在自己的课堂上使用。 调查人员还将指导两个野外营地：一个关于环境微生物学的年度国内营地和一个关于生物矿化的国际野外营地。 学生参与者将学习设计和测试科学假设，通过实地研究，实验室实验和仪器分析（例如，电子显微镜）。 学生们将在年度科学研讨会上展示他们的成果。

There is increasing demand for magnetic nanoparticles in emerging areas of technology and medicine (e.g., high-density data storage, targeted drug delivery, scaffolding for tissue regeneration). The "ideal" particle for many of these applications is a nanometer scale magnet that has defined shape and morphology, narrow size distribution, high crystallinity, and controlled magnetic direction. Magnetotactic bacteria (MTB) have the innate capacity to synthesize crystals of the mineral magnetite (Fe3O4) that meet all of these criteria. In this proposal, investigators will study the protein-directed crystallization of magnetite by MTB. MTB exercise strict genetic control over the size, composition, and morphology of their nanomagnetic crystals. Investigators will examine the so-called Mms proteins (Mms-5, 6, 12, 13; or homologues like MamC) to identify the key catalytic domains that direct nucleation and growth of Fe3O4. In vivo biomineralization experiments will be performed using wild-type strains (e.g., Magnetospirillum magneticum) as well as mutationally altered strains generated during this project. In vitro crystallization experiments will be carried out using recombinant proteins, or peptides that mimic key motifs. Structural and magnetic properties of the in vivo vs. in vitro mineral products will be characterized using electron microscopy, atomic force microscopy, confocal laser scanning microscopy, and magnetometry. Those proteins or peptides that catalyze novel mineral products will be further examined using molecular dynamics simulations in silico. The knowledge to be gained from these studies will allow to fabricate nanometer scale, single domain magnetic crystals that are designed to elicit a particular magnetic response. This project also includes an educational outreach component for middle- and high-school students and teachers. Teachers will spend 3-4 weeks each year with the PIs learning how to collect and isolate MTB from environmental samples as well as characterize MTB with various forms of optical and electron microscopy. Based on this experience, the teachers will design experiments to use in their own classrooms. Investigators will also direct two field camps: an annual, domestic camp on environmental microbiology and one international field camp on biomineralization. Student participants will learn to design and test scientific hypothesis though field studies, lab experiments, and instrumental analyses (e.g., electron microscopy). The students will present their results at an annual science symposium.