The miniF plasmid C protein: sequence, purification and DNA binding.

The C (pifC) protein of miniF represses transcription of its own gene by binding to the pif operator (pifO); it is also needed for replication initiated from the miniF primary origin (ori-1). We have determined the nucleotide sequence of the C gene. The gene has been inserted into an expression vector under Ptrp control where it is expressed at high levels. The C protein has been purified from cells carrying the Ptrp-C plasmid, and a preliminary study of C protein-DNA binding properties has been carried out. C protein binds strongly to pifO, and weakly to sequences in the ori-1 region.