RNA-primed intitiation sites of DNA replication in the origin region of bacteriophage λ genome

Abstract

Using DNA molecules synthesized in the early stage of .lambda. phage infection, deoxynucleotides at the transition sites from primer RNA to DNA synthesis have been mapped in the 1.5 kbase area of the .lambda. phage genome containing the genetically defined replication origin (ori.lambda.). Sites in the 1-strand (the polarity of the 1-strand is 5'' to 3'' from the left to the right direction of the .lambda. phage genetic map) were distributed both inside and outside of the ori.lambda., whereas the sites in the r-strand (the strand in the opposite polarity) were mainly distributed more than three hundred nucleotides apart from the ori.lambda. to the right. A CPuPu sequence was found at -12 to -10 region of transition sites of the r- and the 1-strands in the frequency of 80% and 70%, respectively, and over 60% of the CPuPu sequences were CAG. Properties of the transition sites are discussed in relation to the primer synthesis.