磁小体蛋白的亚细胞定位比较分析揭示了Mms6蛋白在磁铁矿晶体上的独特定位行为。
Comparative Subcellular Localization Analysis of Magnetosome Proteins Reveals a Unique Localization Behavior of Mms6 Protein onto Magnetite Crystals.
作者信息
Arakaki Atsushi, Kikuchi Daiki, Tanaka Masayoshi, Yamagishi Ayana, Yoda Takuto, Matsunaga Tadashi
机构信息
Division of Biotechnology and Life Science, Institute of Engineering, Tokyo University of Agriculture and Technology, Koganei, Tokyo, Japan.
Division of Biotechnology and Life Science, Institute of Engineering, Tokyo University of Agriculture and Technology, Koganei, Tokyo, Japan Department of Chemical Science and Engineering, School of Materials and Chemical Technology, Tokyo Institute of Technology, Meguro-ku, Tokyo, Japan.
出版信息
J Bacteriol. 2016 Sep 22;198(20):2794-802. doi: 10.1128/JB.00280-16. Print 2016 Oct 15.
UNLABELLED
The magnetosome is an organelle specialized for inorganic magnetite crystal synthesis in magnetotactic bacteria. The complex mechanism of magnetosome formation is regulated by magnetosome proteins in a stepwise manner. Protein localization is a key step for magnetosome development; however, a global study of magnetosome protein localization remains to be conducted. Here, we comparatively analyzed the subcellular localization of a series of green fluorescent protein (GFP)-tagged magnetosome proteins. The protein localizations were categorized into 5 groups (short-length linear, middle-length linear, long-length linear, cell membrane, and intracellular dispersing), which were related to the protein functions. Mms6, which regulates magnetite crystal growth, localized along magnetosome chain structures under magnetite-forming (microaerobic) conditions but was dispersed in the cell under nonforming (aerobic) conditions. Correlative fluorescence and electron microscopy analyses revealed that Mms6 preferentially localized to magnetosomes enclosing magnetite crystals. We suggest that a highly organized spatial regulation mechanism controls magnetosome protein localization during magnetosome formation in magnetotactic bacteria.
IMPORTANCE
Magnetotactic bacteria synthesize magnetite (Fe3O4) nanocrystals in a prokaryotic organelle called the magnetosome. This organelle is formed using various magnetosome proteins in multiple steps, including vesicle formation, magnetosome alignment, and magnetite crystal formation, to provide compartmentalized nanospaces for the regulation of iron concentrations and redox conditions, enabling the synthesis of a morphologically controlled magnetite crystal. Thus, to rationalize the complex organelle development, the localization of magnetosome proteins is considered to be highly regulated; however, the mechanisms remain largely unknown. Here, we performed comparative localization analysis of magnetosome proteins that revealed the presence of a spatial regulation mechanism within the linear structure of magnetosomes. This discovery provides evidence of a highly regulated protein localization mechanism for this bacterial organelle development.
未标记
磁小体是趋磁细菌中专门用于无机磁铁矿晶体合成的细胞器。磁小体形成的复杂机制由磁小体蛋白逐步调控。蛋白质定位是磁小体发育的关键步骤；然而，对磁小体蛋白定位的全面研究仍有待开展。在此，我们比较分析了一系列绿色荧光蛋白（GFP）标记的磁小体蛋白的亚细胞定位。蛋白质定位被分为5组（短线性、中线性、长线性、细胞膜和细胞内分散），这与蛋白质功能相关。调节磁铁矿晶体生长的Mms6在形成磁铁矿（微需氧）条件下沿磁小体链结构定位，但在不形成（需氧）条件下分散在细胞中。相关荧光和电子显微镜分析表明，Mms6优先定位于包裹磁铁矿晶体的磁小体上。我们认为，一种高度有序的空间调控机制在趋磁细菌磁小体形成过程中控制磁小体蛋白的定位。
重要性
趋磁细菌在一种称为磁小体的原核细胞器中合成磁铁矿（Fe3O4）纳米晶体。该细胞器通过多种磁小体蛋白分多个步骤形成，包括囊泡形成、磁小体排列和磁铁矿晶体形成，以提供分隔的纳米空间来调节铁浓度和氧化还原条件，从而能够合成形态受控的磁铁矿晶体。因此，为了使这种复杂的细胞器发育合理化，磁小体蛋白的定位被认为受到高度调控；然而，其机制在很大程度上仍不清楚。在此，我们对磁小体蛋白进行了比较定位分析，揭示了磁小体线性结构内存在空间调控机制。这一发现为这种细菌细胞器发育中高度调控的蛋白质定位机制提供了证据。
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