The layered structure of human mtDNA nucleoids
Bogenhagen DF, Rousseau D, Burke S
Journal of Biological Chemistry (2008)
Category: mitochondrial nucleoids ¤ Added: Dec 12, 2007 ¤ Rating: ◊◊
Mitochondrial DNA (mtDNA) occurs in cells in nucleoids containing several copies of the genome. Previous studies have identified proteins associated with these large DNA structures when they are biochemically purified by sedimentation and immunoaffinity chromatography. In this study, formaldehyde crosslinking was performed to determine which nucleoid proteins are in close contact with the mtDNA. A set of core nucleoid proteins is found in both native and crosslinked nucleoids, including 13 proteins with known roles in mtDNA transactions. Several other metabolic proteins and chaperones identified in native nucleoids including ATAD3 were not observed to crosslink to mtDNA. Additional immunofluorescence and protease susceptibility studies showed that an N-terminal domain of ATAD3 previously proposed to bind to the mtDNA D-loop is directed away from the mitochondrial matrix, so that it is unlikely to interact with mtDNA in vivo. These results are discussed in relation to a model for a layered structure of mtDNA nucleoids in which replication and transcription occur in the central core while translation and complex assembly may occur in the peripheral region.