Collaborative Research: Biophysical Analysis of Magnetosome Formation in Magnetotactic Bacteria

许多生物体生存的核心是它们操纵无机分子形成复杂晶体结构的能力，如骨骼、牙齿和保护壳。这种无处不在的“生物矿化”过程依赖于细胞内特殊蛋白质的精确作用，在需要的地方形成矿物质，并防止它们在敏感组织中积累。尽管已经取得了进展，但对于生物矿化是如何在单个细胞内实现的以及哪些基因控制这一过程，人们还不太了解。该合作项目将通过将最新的磁成像技术应用于简单且控制良好的生物系统中生物矿化的详细研究来解决这一挑战：在趋磁细菌（MTB）中产生纳米级磁性颗粒，以及MTB使用这些颗粒链（称为磁小体）定向并沿着地球磁场线行进（称为趋磁）。在这个项目中，学生和博士后研究人员将在物理科学和生命科学的界面上接受科学实践的培训。此外，该项目可能会为具有广泛实际意义的改进材料的开发提供信息，因为生物矿化产品与目前由人类设计的产品相比具有更优越的性能。本项目的科学目标是研究结核分枝杆菌中生物矿化的分子机制和磁性纳米颗粒的发展。该研究将采用“金刚石磁性成像仪”，利用金刚石芯片表面的纳米级量子传感器层，在实验室环境条件下，对单个MTB的磁场模式进行成像，具有优于50纳米的空间分辨率和大于1毫米的视野。研究人员将应用金刚石磁性成像仪研究磁性纳米颗粒在各种结核分枝杆菌和生物矿化突变体中的生长。该项目将为实现趋磁的物理过程打开一个新的窗口，包括磁性纳米颗粒在磁性纳米颗粒生长过程中从超顺磁性到稳定的单畴磁性状态的转变，以及磁性纳米颗粒在单个MTB中相互作用的作用。对基因突变体的磁测量将为控制生物矿化过程的基因提供生物学见解。通过对不同的MTB进行时间序列磁测量以及对单个活MTB进行磁成像，还将观察细胞分裂周期中磁性纳米颗粒链的动力学。

Central to the survival of many organisms is their ability to manipulate inorganic molecules into elaborate crystalline structures such as skeletons, teeth, and protective shells. This ubiquitous process of "biomineralization" depends on the precise action of specialized proteins within cells to form minerals where they are needed and prevent their accumulation in sensitive tissues. Although progress has been made, much is not understood about how biomineralization is realized inside of individual cells and which genes control the process. This collaborative project will address this challenge by applying recent advances in magnetic imaging technology to detailed studies of biomineralization in a simple and well-controlled biological system: the production of nanoscale magnetic particles within magnetotactic bacteria (MTB), and the use by MTB of chains of these particles (known as magnetosomes) for orientation and travel along the Earth's magnetic field lines (known as magnetotaxis). During this project, students and postdoctoral researchers will receive training in scientific practices at the interface of the physical and life sciences. In addition, the project may inform the development of improved materials with broad practical relevance, as products of biomineralization have superior properties compared to those currently engineered by humans.The scientific goals of this project are to study the molecular mechanisms governing biomineralization and the development of magnetic nanoparticles in MTB. The studies will employ a "diamond magnetic imager" that exploits a nanoscale layer of quantum sensors at the surface of a diamond chip, enabling imaging of magnetic field patterns from individual MTB in a population under ambient laboratory conditions, with better than 50 nanometer spatial resolution and greater than 1 millimeter field-of-view. The investigators will apply the diamond magnetic imager to studies of magnetic nanoparticle growth in various MTB species and biomineralization mutants. The project will open a new window onto the physical processes enabling magnetotaxis, including the transition of magnetic nanoparticles from a superparamagnetic to a stable single-domain magnetic state during magnetic nanoparticle growth, and the role of interactions between magnetic nanoparticles within individual MTB. Magnetic measurements on genetic mutants will provide biological insights into the genes controlling the biomineralization process. Observations will also be made of the dynamics of the magnetic nanoparticle chain during the cell division cycle, both through time series magnetic measurements on different MTB as well as magnetic imaging of individual living MTB.