Deletion of the ftsZ-Like Gene Results in the Production of Superparamagnetic Magnetite Magnetosomes in Magnetospirillum gryphiswaldense
Deletion of the ftsZ-Like Gene Results in the Production of Superparamagnetic Magnetite Magnetosomes in Magnetospirillum gryphiswaldense
复制标题
ftsZ-Like 基因的缺失导致 Magnetospirillum gryphiswaldense 中超顺磁性磁铁矿磁小体的产生
DOI：
10.1128/jb.01292-09
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发表时间：
2010-02-01
影响因子：
3.2
通讯作者：
Li, Jilun
中科院分区：
文献类型：
--
作者：
Ding, Yao;Li, Jinhua;Li, Jilun
趋磁性细菌(MTB)合成独特的细胞器，称为“磁小体”，这是一种包含磁铁矿或云母晶体的膜封闭结构。磁小体在MamK细胞骨架细丝周围形成一条链，为MTB沿着地磁线导航以找到最佳微氧栖息地的能力提供了基础。除了编码微管蛋白样FtsZ蛋白的基因(参与细胞分裂)外，结核分枝杆菌属物种的基因组还含有第二个基因，称为FtsZ-like，其功能尚不清楚。在本研究中，我们发现格雷氏磁螺菌MSR-1的类FtsZ基因属于4.9kb的多顺反子转录单位。然后，我们将重组的FtsZ样蛋白纯化到均一。类FtsZ蛋白能有效地降解ATP和GTP，其ATPase和GTP酶活性分别为2.17和5.56 mU/m in。在体外，类FtsZ蛋白通过依赖于GTP的聚合形成长丝状束。为了确定FtsZ-like基因的作用，我们构建了一个FtsZ-like突变体(Delta FtsZ-like突变体)及其互补株(Delta FtsZ-like_C株)。Delta FtsZ样细胞的生长与野生型相似，表明Delta FtsZ样基因不参与细胞分裂。透射电子显微镜观察表明，与野生型细胞相比，Delta FtsZ样细胞产生的磁小体较小，形态模糊，排列不规则，有较大的间隙。磁性分析表明，Delta FtsZ-like主要产生超顺磁性(SP)磁铁矿颗粒，而野生型和Delta FtsZ-like_C细胞主要产生单磁区(SD)颗粒。我们的发现表明，类FtsZ蛋白是合成格氏微囊藻SD颗粒和磁小体所必需的。
Magnetotactic bacteria (MTB) synthesize unique organelles termed "magnetosomes," which are membrane-enclosed structures containing crystals of magnetite or greigite. Magnetosomes form a chain around MamK cytoskeletal filaments and provide the basis for the ability of MTB to navigate along geomagnetic field lines in order to find optimal microaerobic habitats. Genomes of species of the MTB genus Magnetospirillum, in addition to a gene encoding the tubulin-like FtsZ protein (involved in cell division), contain a second gene termed "ftsZ-like," whose function is unknown. In the present study, we found that the ftsZ-like gene of Magnetospirillum gryphiswaldense strain MSR-1 belongs to a 4.9-kb mamXY polycistronic transcription unit. We then purified the recombinant FtsZ-like protein to homogeneity. The FtsZ-like protein efficiently hydrolyzed ATP and GTP, with ATPase and GTPase activity levels of 2.17 and 5.56 mu mol phosphorus per mol protein per min, respectively. The FtsZ-like protein underwent GTP-dependent polymerization into long filamentous bundles in vitro. To determine the role of the ftsZ-like gene, we constructed a ftsZ-like mutant (Delta ftsZ-like mutant) and its complementation strain (Delta ftsZ-like_C strain). Growth of Delta ftsZ-like cells was similar to that of the wild type, indicating that the Delta ftsZ-like gene is not involved in cell division. Transmission electron microscopic observations indicated that the Delta ftsZ-like cells, in comparison to wild-type cells, produced smaller magnetosomes, with poorly defined morphology and irregular alignment, including large gaps. Magnetic analyses showed that Delta ftsZ-like produced mainly superparamagnetic (SP) magnetite particles, whereas wildtype and Delta ftsZ-like_C cells produced mainly single-domain (SD) particles. Our findings suggest that the FtsZ-like protein is required for synthesis of SD particles and magnetosomes in M. gryphiswaldense.