Some DNA or RNA sequences rich in guanine (G) nucleotides can adopt noncanonical
conformations known as G-quadruplexes (G4). In the nuclear genome, G4 motifs
have been associated with genome instability and gene expression defects, but they are increasingly
recognized to be regulatory structures. Recent studies have revealed that G4 structures
can form in the mitochondrial genome (mtDNA) and potential G4 forming sequences
are associated with the origin of mtDNA deletions. However, little is known about the regulatory
role of G4 structures in mitochondria. In this short review, we will explore the potential
for G4 structures to regulate mitochondrial function, based on evidence from the nucleus.