Structural and functional analysis of cloned DNA segments containing the replication and incompatibility regions of a miniplasmid derived from a copy number mutant of NR1

Abstract

1.45-megadalton [Md] megadalton segment of DNA cloned from a miniplasmid derived in vivo from a copy number mutant of the R plasmid NR1 contained all functions essential for incompatibility and autonomous plasmid replication in Escherichia coli. Specific [EcoRI] endonuclease cleavage sites within this DNA segment that localize functions required for replication were mapped. A 0.45 Md fragment that specifies the FII incompatibility of NR1 was identified within the replication region, and DNA fragment containing this incompatibility region, but lacking other functions required for replication, were cloned.