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MamY is a membrane-bound protein that aligns magnetosomes and the motility axis of helical magnetotactic bacteria.
Nature Microbiology ( IF 20.5 ) Pub Date : 2019-07-29 , DOI: 10.1038/s41564-019-0512-8
Mauricio Toro-Nahuelpan 1, 2, 3 , Giacomo Giacomelli 4 , Oliver Raschdorf 1, 2, 5 , Sarah Borg 1, 6 , Jürgen M Plitzko 2 , Marc Bramkamp 4 , Dirk Schüler 1 , Frank-Dietrich Müller 1
Affiliation  

To navigate within the geomagnetic field, magnetotactic bacteria synthesize magnetosomes, which are unique organelles consisting of membrane-enveloped magnetite nanocrystals. In magnetotactic spirilla, magnetosomes become actively organized into chains by the filament-forming actin-like MamK and the adaptor protein MamJ, thereby assembling a magnetic dipole much like a compass needle. However, in Magnetospirillum gryphiswaldense, discontinuous chains are still formed in the absence of MamK. Moreover, these fragmented chains persist in a straight conformation indicating undiscovered structural determinants able to accommodate a bar magnet-like magnetoreceptor in a helical bacterium. Here, we identify MamY, a membrane-bound protein that generates a sophisticated mechanical scaffold for magnetosomes. MamY localizes linearly along the positive inner cell curvature (the geodetic cell axis), probably by self-interaction and curvature sensing. In a mamY deletion mutant, magnetosome chains detach from the geodetic axis and fail to accommodate a straight conformation coinciding with reduced cellular magnetic orientation. Codeletion of mamKY completely abolishes chain formation, whereas on synthetic tethering of magnetosomes to MamY, the chain configuration is regained, emphasizing the structural properties of the protein. Our results suggest MamY is membrane-anchored mechanical scaffold that is essential to align the motility axis of magnetotactic spirilla with their magnetic moment vector and to perfectly reconcile magnetoreception with swimming direction.

中文翻译:

MamY 是一种膜结合蛋白,可对齐磁小体和螺旋趋磁细菌的运动轴。

为了在地磁场中导航,趋磁细菌合成磁小体,这是由膜包裹的磁铁矿纳米晶体组成的独特细胞器。在趋磁螺旋体中,磁小体被​​形成细丝的肌动蛋白样 MamK 和衔接蛋白 MamJ 积极组织成链,从而组装成一个磁偶极子,就像指南针一样。然而,在 Magnetospirillum gryphiswaldense 中,在没有 MamK 的情况下仍会形成不连续的链。此外,这些碎片链以直线构象持续存在,表明未发现的结构决定因素能够容纳螺旋细菌中的条形磁铁状磁感受器。在这里,我们确定了 MamY,这是一种膜结合蛋白,可为磁小体生成复杂的机械支架。MamY 沿细胞内正曲率(大地细胞轴)线性定位,可能是通过自相互作用和曲率传感。在一个mamY 缺失突变体中,磁小体链从测地轴分离并且不能适应与减少的细胞磁取向一致的直构象。MamKY 的共缺失完全消除了链的形成,而在将磁小体合成束缚到 MamY 时,链配置被重新获得,强调了蛋白质的结构特性。我们的研究结果表明,MamY 是膜锚定的机械支架,对于将趋磁螺旋体的运动轴与其磁矩矢量对齐以及完美地协调磁感应与游泳方向至关重要。在一个mamY 缺失突变体中,磁小体链从测地轴分离并且不能适应与减少的细胞磁取向一致的直构象。MamKY 的共缺失完全消除了链的形成,而在将磁小体合成束缚到 MamY 时,链配置被重新获得,强调了蛋白质的结构特性。我们的研究结果表明,MamY 是膜锚定的机械支架,对于将趋磁螺旋体的运动轴与其磁矩矢量对齐以及完美地协调磁感应与游泳方向至关重要。在一个mamY 缺失突变体中,磁小体链从测地轴分离并且不能适应与减少的细胞磁取向一致的直构象。MamKY 的共缺失完全消除了链的形成,而在将磁小体合成束缚到 MamY 时,链配置被重新获得,强调了蛋白质的结构特性。我们的研究结果表明,MamY 是膜锚定的机械支架,对于将趋磁螺旋体的运动轴与其磁矩矢量对齐以及完美地协调磁感应与游泳方向至关重要。而在将磁小体合成束缚到 MamY 时,链结构被重新获得,强调了蛋白质的结构特性。我们的研究结果表明,MamY 是膜锚定的机械支架,对于将趋磁螺旋体的运动轴与其磁矩矢量对齐以及完美地协调磁感应与游泳方向至关重要。而在将磁小体合成束缚到 MamY 时,链结构被重新获得,强调了蛋白质的结构特性。我们的研究结果表明,MamY 是膜锚定的机械支架,对于将趋磁螺旋体的运动轴与其磁矩矢量对齐以及完美地协调磁感应与游泳方向至关重要。
更新日期:2019-07-30
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