Abstract
A detailed physical and functional map of the chloramphenicol (Cm) resistance plasmid pC223 from Staphylococcus aureus was compiled. The plasmid's basic replicon and origin of replication were located and their nucleotide sequences determined. Two small RNAs of 92 and 155 nt, demonstrated by in vitro transcription with vegetative Bacillus subtilis RNA polymerase, were depicted as copy number regulating (cop) and incompatibility (inc) functions in Bacillus subtilis. pC223 and pUB112, another S. aureus Cm resistance plasmid, which exhibits marked sequence homology with pC223 and codes also for two small copRNAs, could be classified as members of the pT181-plasmid family (1). Copy numbers and segregational instability of pC223, pUB112 and deletion derivatives of both in B. subtilis showed great differences despite of their homologous basic replicons.