Has both DNA primase and DNA helicase activities and may be involved in organelle DNA replication. Capable of producing RNA primers of 9 to 18 bases from a single-stranded DNA template. ATP + H2O = ADP + H(+) + phosphate Binds two Mg(2+) per subunit. Expressed in young leaves and shoot apex tissues. Detected in developing tissues such as cotyledons, sepals, pistils and inflorescences. Nearly undetectable in mature leaves.