Expression, Purification, and In Vitro Assays of Mitochondrial Single-Stranded DNA-Binding Protein

The mitochondrial single-stranded DNA-binding protein (mtSSB) is encoded by a single-copy nuclear gene in mammals. After de novo synthesis in the cytosol, mtSSB is transported into mitochondria, where it participates in mitochondrial DNA (mtDNA) replication, RNA transcription, and maintenance of mitochondrial DNA D-loop structure (1 –3 ). Mitochondrial SSB requires three different types of intermolecular interaction for its function: self association to form homotetramers, binding to single-stranded DNA (ssDNA), and interaction with other proteins (4 –7 ).