Topoisomerase I, Mitochondrial (TOP1MT)

TOP1MT is a mitochondrial DNA topoisomerase, an enzyme that controls and alters the topologic states of DNA during transcription. This enzyme catalyzes the transient breaking and rejoining of DNA which allows the strands to pass through one another and relieves the stress introduced by a circular mitochondrial genome during replication and transcription. TOP1MT, encoding a 601-amino acid polypeptide that is highly homologous to nuclear topoisomerase I (TOP1). The N-terminal domain of TOP1MT contains a mitochondrial localization sequence and lacks a nuclear localization signal. The pattern of TOP1MT expression matches the requirement for high mitochondrial activity in specific tissues. TOP1MT is a type IB topoisomerase and requires divalent metal, Ca(2+) or Mg(2+), and alkaline pH for optimal activity.