趨磁性細菌利用一種被稱為“磁小體”的專門化細胞器（磁鐵礦(Fe(II)Fe(III)2O4)或硫復鐵礦(Fe(II)Fe(III)2S4)的一種生物礦化晶體）來探測地球磁場,，并與其方向保持一致,。

這篇論文介紹了與“磁小體”相結合的蛋白MamP的X-射線晶體結構，它顯示了由融合到兩個“磁小體”域上的一個“自插入”（self-plugged）PDZ域構成的一個獨特排列,。

作者還確定,，MamP是一個鐵氧化酶,，有助于“三價鐵”水鐵礦的形成,，因此對于在“磁小體”生物生成過程中的鐵管理機制很重要。（生物谷Bioon.com)

生物谷推薦的英文摘要

Nature       doi:10.1038/nature12573

Structural insight into magnetochrome-mediated magnetite biomineralization

Marina I. Siponen,，Pierre Legrand,，Marc Widdrat，Stephanie R. Jones,，Wei-Jia Zhang,，Michelle C. Y. Chang，Damien Faivre,，Pascal Arnoux& David Pignol

Magnetotactic bacteria align along the Earth’s magnetic field using an organelle called the magnetosome,， a biomineralized magnetite (Fe(ii)Fe(iii)2O4) or greigite (Fe(ii)Fe(iii)2S4) crystal embedded in a lipid vesicle. Although the need for both iron(ii) and iron(iii) is clear， little is known about the biological mechanisms controlling their ratio1. Here we present the structure of the magnetosome-associated protein MamP and find that it is built on a unique arrangement of a self-plugged PDZ domain fused to two magnetochrome domains,， defining a new class of c-type cytochrome exclusively found in magnetotactic bacteria. Mutational analysis,， enzyme kinetics， co-crystallization with iron(ii) and an in vitro MamP-assisted magnetite production assay establish MamP as an iron oxidase that contributes to the formation of iron(iii) ferrihydrite eventually required for magnetite crystal growth in vivo. These results demonstrate the molecular mechanisms of iron management taking place inside the magnetosome and highlight the role of magnetochrome in iron biomineralization.