Structural characterization of encapsulated ferritin provides insight into iron storage in bacterial nanocompartments
Structural characterization of encapsulated ferritin provides insight into iron storage in bacterial nanocompartments
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DOI：
10.7554/elife.18972
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发表时间：
2016-08-16
期刊：
影响因子：
7.7
通讯作者：
Marles-Wright, Jon
中科院分区：
文献类型：
--
作者：
He, Didi;Hughes, Sam;Marles-Wright, Jon
铁蛋白是一种普遍存在的蛋白质，它能在蛋白质外壳内氧化并储存铁，以保护细胞免受氧化损伤。我们已经对铁蛋白超家族中一个被隔离在封装蛋白衣壳内的新成员的结构和功能进行了表征。我们发现这种被封装的铁蛋白（EncFtn）有两条主要的α螺旋，它们以一种依赖金属的方式组装，在二聚体界面形成一个铁氧化酶中心。EncFtn采用一种开放的十聚体结构，在拓扑学上与其他铁蛋白不同。虽然EncFtn起到铁氧化酶的作用，但它不能使铁矿化。相反，封装蛋白外壳与铁结合，但没有酶活性，并且我们证明EncFtn必须位于封装蛋白内才能储存铁。这种封装蛋白纳米隔室在细菌和古菌中广泛分布，代表了一种独特的铁储存系统，其中铁的氧化和矿化作用分布在两种蛋白质之间。
Ferritins are ubiquitous proteins that oxidise and store iron within a protein shell to protect cells from oxidative damage. We have characterized the structure and function of a new member of the ferritin superfamily that is sequestered within an encapsulin capsid. We show that this encapsulated ferritin (EncFtn) has two main alpha helices, which assemble in a metal dependent manner to form a ferroxidase center at a dimer interface. EncFtn adopts an open decameric structure that is topologically distinct from other ferritins. While EncFtn acts as a ferroxidase, it cannot mineralize iron. Conversely, the encapsulin shell associates with iron, but is not enzymatically active, and we demonstrate that EncFtn must be housed within the encapsulin for iron storage. This encapsulin nanocompartment is widely distributed in bacteria and archaea and represents a distinct class of iron storage system, where the oxidation and mineralization of iron are distributed between two proteins.