Detection of primase specified by IncB plasmid R864a

Plasmid R864a (IncB) contains nucleotide sequences homologous with the sog primase determinant of IncI alpha plasmid ColIb-P9. Extracts of Escherichia coli carrying a mutant R864a derepressed for transfer functions showed enhanced primase activity, and contained a large polypeptide identical in size (apparent Mr = 220,000) to the IncI alpha sog gene product.