Abstract
Mini-F plasmid has three genes sopA, sopB and sopC essential for partitioning the plasmid. The sopA and sopB genes code for 43.7Kd and 35.4Kd proteins, respectively. The cis-acting sopC region has twelve 43-bp direct repeats. Purified SopB protein binds to the sopC DNA. SopA protein acts as the repressor of the sopA-sopB operon in the presence of SopB protein. When plasmid-free segregants appear in cell division, they are killed postsegregationally by the ccd mechanism controlled by the ccdA and ccdB gene products of the plasmed.
