FIG. 4.

Diagram showing the experiment performed to determine the minimum DNA fragment from rep₂₀₀₉ that confers a Per phenotype on UC509.9. Synthetic oligonucleotide primers were designed to generate subfragments spanning the rep₂₀₀₉ gene by PCR. These fragments were then cloned in pNZ8048 and introduced into UC509.9. Plaque assay and lysis-in-broth experiments were performed to determine which fragments conferred a Per phenotype, which is indicated in the column labelled Per. Radioactive probes, made from these rep₂₀₀₉ subfragments, were used in gel retardation experiments to determine if the Rep₂₀₀₉ protein was capable of binding to the fragments (column labelled Binds Rep₂₀₀₉). Arrows indicate the positions of the repeated sequences contained within ori₂₀₀₉. ∗, the Per effect conferred by this DNA fragment was not as strong as that conferred by other Per⁺ DNA fragments.