CHROMOSOME REPLICATION IN ESCHERICHIA COLI .2. ORIGIN OF REPLICATION IN F- AND F+ STRAINS

It is shown that an F- and an F+ strain of Escherichia coli K12 W1485 have a unique origin for replication of their chromosome, located between argG and xyl, close to xyl, and the direction of replication is clockwise. Many different strains, of all mating types, of E. coli K12 are found to have the same direction of replication and an origin similarly located. The preferred point of initiation during recovery from amino acid starvation is identified as the origin of vegetative replication. It is found, however, that during starvation most chromosomes of E. coli K12 are unable to complete a full replication cycle. © 1969.