About TFB / Mitochondrial Transcription Factor:
Mitochondrial transcription factor A (TFAM or mtTFA) is a protein encoded by the TFAM gene in humans. TFAM is a DNA-binding and bending protein with a double box high-mobility group. In mammals, this bending action is required for mitochondrial transcription initiation, but not in yeasts with the homolog Abf2. Because its binding activity is non-sequence specific, TFAM may also play a role in mitochondrial genome packaging.
A growing body of evidence suggests that mammalian mitochondrial DNA adopts a higher structure known as a nucleoid or mito chromosome, corresponding to nuclear DNA. Mitochondrial transcription factor A (TFAM), which was cloned as a transcription factor for mitochondrial DNA, is known to be required for mitochondrial DNA maintenance.
Mitochondrial Transcription Factor Mechanism
Human TFAM has the ability to bind to DNA in a sequence-independent manner. It is abundant enough to cover the entire region of mitochondrial DNA, resulting from which TFAM stabilizes mitochondrial DNA via nucleoid formation and regulates (or titrates) the amount of mitochondrial DNA. Human TFAM overexpression in mice increases the amount of mitochondrial DNA and significantly improves the cardiac dysfunctions caused by myocardial infarction. The integrity of mitochondrial DNA is critical for maintaining proper cellular functions under both physiological and pathological conditions. TFAM may be important in maintaining mitochondrial DNA as a nucleoid component.
All of this points to TFAM as a candidate among the mitochondrial proteins that recognize G4s. Based on this, it has been discovered that human TFAM binds to DNA and RNA G4s in a structure-specific manner with high affinity and versatility.