Illegitimate recombination occurs between the replication origin of the plasmid pC194 and a progressing replication fork.

Hybrids between plasmids pC194, pBR322 and the bacteriophage f1 undergo deletions in Escherichia coli. The deletions end most often between nucleotides 1445 and 1446 of pC194. That site probably corresponds to a nick in the replication origin of this plasmid. The localization of the other deletion end appears to be determined by the position of the f1 replication fork. Two models accounting for these data are discussed.