The Mitochondrial Transcription Factor TFAM Coordinates the Assembly of Multiple DNA Molecules into Nucleoid-like Structures

• DOI: 10.1091/mbc.e07-05-0404
• Publication Date: 2007-06-21T01:40:37Z
• Authors: Brett A. Kaufman; Nela Durisic; Jeffrey M. Mative...; Santiago Costantino; Mark A. Hancock; Peter Grutter; Eric A. Shoubridge
• Keywords: Nucleoid; TFAM

Packaging DNA into condensed structures is integral to the transmission of genomes. The mammalian mitochondrial genome (mtDNA) a high copy, maternally inherited in which mutations cause variety multisystem disorders. In all eukaryotic cells, multiple mtDNAs are packaged with protein spheroid bodies called nucleoids, fundamental units mtDNA segregation. mechanism nucleoid formation, however, remains unknown. Here, we show that transcription factor TFAM, an abundant and highly conserved High Mobility Group box protein, binds cooperatively nanomolar affinity as homodimer it capable coordinating fully compacting several molecules together form structures. We use noncontact atomic force microscopy, achieves near cryo-electron microscope resolution, reveal structural details protein–DNA compaction intermediates. formation these complexes involves bending backbone, loop followed by filling proximal available sites until compacted. These results indicate TFAM alone sufficient organize chromatin provide for formation.