Strand Displacement -When new synthesis starts at a nick it displaces a strand. The displaced strand then itself becomes a template for the synthesis of a new strand. The first example was reported in E coli, where DNA polymerase I starts at a nick and catalyses the displacement of a strand just ahead of itself. In the phage TS also DNA polymerase promotes strand displacement. In the phage T7 gene 4 protein, a DNA-dependent ribonuc1eoside-5'-triphosphatase promotes strand displacement by unwinding the DNA.
