Capable of resolving Holliday junctions. Specific for 4-way junctions. Seems to be important for the maintenance of mitochondrial DNA. Cleaves fixed junctions at the point of strand exchange. Cleaves after 5'-CT-3' and 5'-TT-3' sequences. Endonucleolytic cleavage at a junction such as a reciprocal single-stranded crossover between two homologous DNA duplexes (Holliday junction). Homodimer.