CHARACTERIZATION OF BACTERIAL-CELL MEMBRANE ATTACHMENT SITES OF PLASMID R6K

In vitro binding studies revealed that plasmid R6K could attach to bot h inner and outer membrane fractions of its host cell, Escherichia col i. Derivatives of R6K carrying one or two of its three origins of repl ication could not bind stably to the same membrane fractions in the pr esence of salt. However, the derivative, pRK35, carrying the intact th ree origins of replication could bind stably to membrane fractions fro m its host in the presence or absence of salt. These observations sugg est that the three origins of DNA replication must be contiguous for s table binding of the plasmid to the cell membrane. The results of bind ing experiments showed that plasmid R6K bound competitively with pRK35 as well as the heterologous plasmid, p1524. (C) 1996 Academic Press, Inc.