Role of the magnetosome proteins MamGFDC in biomineralization and size control of magnetite crystals in Magnetospirillum gryphiswaldense

细菌磁小体是一种独特的原核细胞器，由膜结合的磁铁矿纳米晶体组成，用于磁导航。一个尚未解决的主要问题是如何精确调节磁小体生物矿化以实现磁铁矿纳米晶体的结构完善、特征形状和均匀尺寸。在gryphiswaldense磁螺旋体中丰富的与磁小体相关的MamGFDC蛋白代表了与磁小体大小控制有关的第一个生物学决定因素，尽管它们的确切功能尚不清楚。我们将对MamGFDC和相关的MmsF蛋白进行表征，并阐明它们干扰磁铁矿生物矿化的机制。通过遗传分析，我们将估计它们的个体对大小控制的贡献。可控的mamGFDC表达将用于合成尺寸修饰的磁性纳米颗粒。野生型和突变型蛋白的细胞内定位和相互作用将通过生化方法和荧光显微镜进行研究。结合磁铁矿和直接干扰其结晶的潜力将在体外进行评估。我们的研究可能有助于为生物技术应用定制磁性纳米颗粒的生物合成，也可能有助于提高对铁生物矿物有机/无机界面生物分子相互作用的理解。

Bacterial magnetosomes are unique prokaryotic organelles consisting of membrane-bounded magnetite nanocrystals that are synthesized for magnetic navigation. One major unsolved question is how magnetosome biomineralization is precisely regulated to achieve the structural perfection, characteristic shapes and uniform sizes of magnetite nanocrystals. The abundant magnetosome-associated MamGFDC proteins in the bacterium Magnetospirillum gryphiswaldense represent the first biological determinants implicated in size control of magnetosomes, although their precise functions are still unknown. We will characterize MamGFDC and the related MmsF protein and elucidate the mechanism by which they interfere with magnetite biomineralization. By genetic analysis we will estimate their individual contributions to size control. Controlled mamGFDC expression will then be used for the synthesis of size-modified magnetic nanoparticles. The intracellular localization and interaction of wild-type and mutant proteins will be studied by biochemical methods and fluorescence microscopy. The potential to bind magnetite and to directly interfere with its crystallization will be assessed in vitro. Our studies may facilitate the biogenic synthesis of tailored magnetic nanoparticles for biotechnological applications and may also contribute to an improved understanding of biomolecular interactions at the organic/inorganic interface of iron biominerals.