Role of Saccharomyces cerevisiae ISA1 and ISA2 in iron homeostasis
Role of Saccharomyces cerevisiae ISA1 and ISA2 in iron homeostasis
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DOI：
10.1128/mcb.20.11.3918-3927.2000
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发表时间：
2000-06-01
影响因子：
5.3
通讯作者：
Culotta, VC
中科院分区：
文献类型：
--
作者：
Jensen, LT;Culotta, VC
芽殖酵母酿酒酵母（Saccharomyces cerevisiae）含有细菌IscA蛋白的两个同源物，命名为Isa 1 p和Isa 2 p。细菌IscA是伊势（铁硫簇）操纵子的产物，并且已被建议参与Fe-S簇的形成或修复。为了测试酵母Isa 1 p和Isa 2 p的功能，在ISA 1和ISA 2中引入单一或组合破坏。所得到的伊萨Delta突变体是可行的，但表现出依赖赖氨酸和谷氨酸盐的生长和呼吸缺陷，由于线粒体DNA中的突变的积累。与其他酵母基因提出的功能在Fe-S簇组装，线粒体铁浓度显着升高的伊萨突变体中，和活动的Fe-S簇含乌头酸酶和琥珀酸脱氢酶显着降低。对从细菌到哺乳动物的ISA样蛋白的检查显示了三个不变的半胱氨酸残基，在Isa 1 p和Isa 2 p的情况下，这是功能所必需的，并且可能参与铁结合。正如预测的那样，Isa 1 p靶向线粒体基质。然而，Isa 2 p存在于线粒体的膜间隙内。我们的缺失分析显示，Isa 2 p含有一个二分的N-末端前导序列，该序列含有与第二序列相连的线粒体输入信号，该第二序列将Isa 2 p靶向膜间隙。Isa 2 p功能需要这两个信号。Isa 1 p和Isa 2 p的非冗余的作用，在提供铁的Fe-S簇组装的网站的模型进行了讨论。
The budding yeast Saccharomyces cerevisiae contains two homologues of bacterial IscA proteins, designated Isa1p and Isa2p, Bacterial IscA is a product of the ise (iron-sulfur cluster) operon and has been suggested to participate in Fe-S cluster formation or repair. To test the function of yeast Isa1p and Isa2p, single or combinatorial disruptions were introduced in ISA1 and ISA2. The resultant isa Delta mutants were viable but exhibited a dependency on lysine and glutamate for growth and a respiratory deficiency due to an accumulation of mutations in mitochondrial DNA. As with other yeast genes proposed to function in Fe-S cluster assembly, mitochondrial iron concentration was significantly elevated in the isa mutants, and the activities of the Fe-S cluster-containing enzymes aconitase and succinate dehydrogenase were dramatically reduced. An inspection of Isa-like proteins from bacteria to mammals revealed three invariant cysteine residues, which in the case of Isa1p and Isa2p are essential for function and may be involved in iron binding. As predicted, Isa1p is targeted to the mitochondrial matrix. However, Isa2p is present within the intermembrane space of the mitochondria. Our deletion analyses revealed that Isa2p harbors a bipartite N-terminal leader sequence containing a mitochondrial import signal linked to a second sequence that targets Isa2p to the intermembrane space. Both signals are needed for Isa2p function. A model for the nonredundant roles of Isa1p and Isa2p in delivering iron to sites of the Fe-S cluster assembly is discussed.