Replication origins/Overview

The genetic element responsible for the replication of plasmids during cell growth and division is called a replication origin (also "origin of replication" or simply "origin"). There are several different replication origins and they differ in their plasmid copy number per cell (how many molecules of the plasmid are maintained in the cell), mechanism of copy number control, cell-to-cell copy number variation, and even the degree of coiling of the physical DNA. Thus, BioBrick® parts, devices and systems can operate very differently from one plasmid backbone to another.

Several replication origins have been designed in the Registry. Although most of them are not available as individual BioBrick parts, some can be obtained by PCR of existing plasmid backbones in the Registry using appropriate primers. In fact, when making new BioBrick vectors using the BioBrick base vector, Reshma simply assembled a PCR-amplified linear DNA encoding the replication origins with the antibiotic resistance markers. (The PCR primers included the BioBrick prefix and suffix so that the linear DNA encoding the origin was ready for digestion with EcoRI and SpeI.