PDIP38 associates with proteins constituting the mitochondrial DNA nucleoid

Xiaoli Cheng, Tomotake Kanki, Atsushi Fukuoh, Kippei Ohgaki, Ryu Takeya, Yoshimasa Aoki, Naotaka Hamasaki, Dongchon Kang

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64 Citations (Scopus)


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 δ. 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.

Original languageEnglish
Pages (from-to)673-678
Number of pages6
JournalJournal of biochemistry
Issue number6
Publication statusPublished - Dec 2005

All Science Journal Classification (ASJC) codes

  • Medicine(all)


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