Nucleoside diphosphate kinase of Saccharomyces cerevisiae, Ynk1p:: localization to the mitochondrial intermembrane space
Nucleoside diphosphate kinase of Saccharomyces cerevisiae, Ynk1p:: localization to the mitochondrial intermembrane space
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DOI：
10.1042/bj20021415
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发表时间：
2003-03-15
影响因子：
4.1
通讯作者：
Pain, D
中科院分区：
文献类型：
--
作者：
Amutha, B;Pain, D
核苷二磷酸激酶（NDPK）是一种高度保守的多功能酶。它催化γ磷酸盐从核苷三磷酸到核苷二磷酸的转移，其机制涉及自磷酸化酶中间体的形成。磷酸通常由ATP提供。不同亚细胞区室的NDPK活性可能调节ATP和GTP或其他核苷三磷酸之间的关键平衡。NDPKs是同源寡聚蛋白，主要定位于细胞质中。在本文中，我们证明了在酿酒酵母中，YNK1编码的NDPK总活性的一小部分存在于线粒体的膜间空间（IMS）中，IMS中相应的蛋白Ynk I p代表了大约。总线粒体蛋白的0.005%。Ynk1p作为单基因产物合成，因此必须在细胞质和线粒体IMS组分之间进行分割。我们的观察提示了这种分配的机制，即与线粒体外膜转位酶（Tom40p）的40 kDa蛋白的相互作用优先发生在未折叠的、未磷酸化的Ynk1p形式上。新翻译但尚未折叠或自磷酸化的Ynk1p中间体可能被输入线粒体的IMS，并通过随后的折叠和寡聚化被困在那里。在IMS的小体积内，Ynk1p可能更集中，可能需要向该隔室中的几种重要蛋白质提供GTP。
Nucleoside diphosphate kinase (NDPK) is a highly conserved multifunctional enzyme. It catalyses the transfer of gamma phosphates from nucleoside triphosphates to nucleoside diphosphates by a mechanism that involves formation of an autophosphorylated enzyme intermediate. The phosphate is usually supplied by ATP. NDPK activity in different subcellular compartments may regulate the crucial balance between ATP and GTP or other nucleoside triphosphates. NDPKs are homo-oligomeric proteins and are predominantly localized in the cytosol. In this paper, we demonstrate that in Saccharomyces cerevisiae a small fraction of total NDPK activity encoded by YNK1 is present in the intermembrane space (IMS) of mitochondria, and the corresponding protein Ynk I p in the IMS represents approx. 0.005 % of total mitochondrial proteins. Ynk1p, synthesized as a single gene product, must therefore be partitioned between cytoplasm and mitochondrial IMS fractions. A mechanism for this partitioning is suggested by our observations that interaction with a 40 kDa protein of the translocase of outer mitochondrial membrane (Tom40p), occurs preferentially with unfolded, unphosphorylated forms of Ynk1p. A population of newly translated, but not yet folded or autophosphorylated, Ynk1p intermediates may be imported into the IMS of mitochondria and trapped there by subsequent folding and oligomerization. Within the small volume of the IMS, Ynk1p maybe more concentrated and may be required to supply GTP to several important proteins in this compartment.