Prokaryotic promoters in the chloroplast DNA replication origin of Chlamydomonas reinhardtii.

In Chlamydomonas reinhardtii, one displacement loop region which initiates the replication of chloroplast DNA was located on a 1.05 kb restriction fragment. This fragment was cloned and sequenced. In this report, the galK expression plasmid, pKO1 was used to screen for the presence of any prokaryotic promoter within the cloned fragment. The insertion of 2 AluI fragments yielded galK+ colonies. Sequence analyses of these AluI inserts revealed prokaryotic promoter consensus regions. Cloning into pKOTWI and subsequent DNA sequencing were used to determine the promoter-active orientation of each insert. Two back-to-back prokaryotic promoters were mapped on a 79 bp AluI fragment located within the displacement loop region.