PDIP38 associates with proteins constituting the mitochondrial DNA nucleoid
PDIP38 associates with proteins constituting the mitochondrial DNA nucleoid
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DOI：
10.1093/jb/mvi169
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发表时间：
2005-12-01
影响因子：
2.7
通讯作者：
Kang, DC
中科院分区：
文献类型：
--
作者：
Cheng, XL;Kanki, T;Kang, DC
人类线粒体DNA呈现一个巨大的蛋白质-DNA复合体，称为类核或有丝分裂染色体。线粒体转录因子A(TFAM)是该复合体的主要成分。在试图用蛋白质组学方法寻找与含有TFAM的复合体相关的蛋白质时，我们发现了一种尚未被认为是线粒体的蛋白质：PDIP38。PDIP38最初被鉴定为核DNA聚合酶Delta的结合蛋白。PDIP38几乎完全从人HeLa细胞的线粒体片段中回收。当TritonX-100溶解的线粒体用蛋白酶K处理时，PDIP38被完全切割，而当没有外膜的线粒体被处理时，PDIP38不被切割，这表明PDIP38位于线粒体基质中。TFAM和线粒体单链DNA结合蛋白(MtSSB)通过抗PDIP38抗体与PDIP38免疫共沉淀。另一方面，当线粒体用交联剂甲醛处理时，只有后者与PDIP38交联。除了mtSSB外，60 kDa热休克蛋白和Lon蛋白同源物也是交联的，它们都具有单链DNA结合活性。PDIP38与类核成分有关，可能参与线粒体DNA的代谢。
Human mitochondrial DNA takes on a large protein-DNA complex called a nucleoid or mitochromosome. Mitochondrial transcription factor A (TFAM) is a major component of the complex. During an attempt to search for proteins associated with the TFAM-containing complex by a proteomic method, we found one protein that has not been considered to be mitochondrial: PDIP38. PDIP38 was initially identified as a binding protein to nuclear DNA polymerase delta. PDIP38 is almost exclusively recovered from the mitochondrial fraction of human HeLa cells. PDIP38 is completely cleaved when TritonX-100-solubilized mitochondria are treated with proteinase K, but not when mitoplasts devoid of outer membranes are treated, indicating that PDIP38 is located in the mitochondrial matrix. TFAM and mitochondrial single-stranded DNA binding protein (mtSSB) are co-immunoprecipitated with PDIP38 by anti-PDIP38 antibodies. On the other hand, only the latter is crosslinked to PDIP38 when mitochondria are treated with a crosslinker, formaldehyde. In addition to mtSSB, 60 kDa heat shock protein and a Lon protease homolog, both of which have single-stranded DNA binding activity, are also crosslinked. PDIP38 associates with the nucleoid components and could be involved in the metabolism of mitochondrial DNA.