Schüler Dirk
Faculty of Biology, Microbiology, Ludwig Maximilians University, München, Germany.
FEMS Microbiol Rev. 2008 Jul;32(4):654-72. doi: 10.1111/j.1574-6976.2008.00116.x. Epub 2008 Jun 2.
The ability of magnetotactic bacteria (MTB) to orient in magnetic fields is based on the synthesis of magnetosomes, which are unique prokaryotic organelles comprising membrane-enveloped, nano-sized crystals of a magnetic iron mineral that are aligned in well-ordered intracellular chains. Magnetosome crystals have species-specific morphologies, sizes, and arrangements. The magnetosome membrane, which originates from the cytoplasmic membrane by invagination, represents a distinct subcellular compartment and has a unique biochemical composition. The roughly 20 magnetosome-specific proteins have functions in vesicle formation, magnetosomal iron transport, and the control of crystallization and intracellular arrangement of magnetite particles. The assembly of magnetosome chains is under genetic control and involves the action of an acidic protein that links magnetosomes to a novel cytoskeletal structure, presumably formed by a specific actin-like protein. A total of 28 conserved genes present in various magnetic bacteria were identified to be specifically associated with the magnetotactic phenotype, most of which are located in the genomic magnetosome island. The unique properties of magnetosomes attracted broad interdisciplinary interest, and MTB have recently emerged as a model to study prokaryotic organelle formation and evolution.
趋磁细菌（MTB）在磁场中定向的能力基于磁小体的合成，磁小体是独特的原核细胞器，由膜包裹的磁性铁矿物纳米晶体组成，这些晶体在细胞内排列成有序的链状。磁小体晶体具有物种特异性的形态、大小和排列方式。磁小体膜通过内陷起源于细胞质膜，代表一个独特的亚细胞区室，具有独特的生化组成。大约20种磁小体特异性蛋白在囊泡形成、磁小体铁运输以及磁铁矿颗粒的结晶和细胞内排列控制中发挥作用。磁小体链的组装受遗传控制，涉及一种酸性蛋白的作用，该蛋白将磁小体连接到一种可能由特定肌动蛋白样蛋白形成的新型细胞骨架结构上。已确定存在于各种磁性细菌中的总共28个保守基因与趋磁表型特异性相关，其中大多数位于基因组磁小体岛中。磁小体的独特性质引起了广泛的跨学科兴趣，最近趋磁细菌已成为研究原核细胞器形成和进化的模型。
