A regulatory protein of mitochondrial expression purified by affinity chromatography with synthetic oligonucleotides

A peculiar feature of vertrebate mitochondrila genomes is the presence of a main non coding region which contains the regulatory elements for the replication and expression of mtDNA. This region spans between the Phe- and Pro-tRNAs genes. It is called D-loop containing region because of the three-stranded displacement (D) loop structure, created by the nascent heavy (H) strand at the level of the H-strand replication origin (Ori-H). It also contains promoters for teh transcription of both the heavy strand (HSP) and the light strand (LSP). This region is the target site for numerous enzymes, such as DNA and RNA polymerases and protein regultory factors. Since all these proteins are coded by nulcear DNA, motichondrial biogenesis involves intricate control circuits relevant to nucleus-mitochondiron coevolution. In a previous paper, we described a peculiar feature of this region in rat mtDNA, a sequence-dependent DNA curvature localized upstream the Ori-H and LSP. By gel shift assay, this structure appeared to be involved in interactions with protein components. Here we report the isolation and characterization of the protein factor(s) by affinity chromatography which uses specific oligonucleotides.