title: PDIP38 associates with proteins constituting the mitochondrial DNA nucleoid.
abstract: 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.
authors.affiliation: Department of Clinical Chemistry and Laboratory Medicine, Kyushu University Graduate School of Medical Sciences, Fukuoka 812-8582.
authors.forename: Xiaoli
authors.initials: X
authors.lastname: Cheng
authors.forename: Tomotake
authors.initials: T
authors.lastname: Kanki
authors.forename: Atsushi
authors.initials: A
authors.lastname: Fukuoh
authors.forename: Kippei
authors.initials: K
authors.lastname: Ohgaki
authors.forename: Ryu
authors.initials: R
authors.lastname: Takeya
authors.forename: Yoshimasa
authors.initials: Y
authors.lastname: Aoki
authors.forename: Naotaka
authors.initials: N
authors.lastname: Hamasaki
authors.forename: Dongchon
authors.initials: D
authors.lastname: Kang
mesh_terms: D004272:DNA, Mitochondrial; D004277:DNA, Single-Stranded / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000378:metabolism*; D006367:HeLa Cells; D006801:Humans; D024101:Mitochondrial Proteins / Q000378:metabolism*; D009687:Nuclear Proteins / Q000378:metabolism* / Q000502:physiology; D011485:Protein Binding; D014157:Transcription Factors / Q000378:metabolism*
chemical_list: D004272:DNA, Mitochondrial; D004277:DNA, Single-Stranded; D004268:DNA-Binding Proteins; D024101:Mitochondrial Proteins; D009687:Nuclear Proteins; C473592:POLDIP2 protein, human; C499631:TFAM protein, human; D014157:Transcription Factors