Novel mutants of Escherichia coli that accumulate very small DNA replicative intermediates

A new group of mutants has been isolated which, during short pulses, incorporate (3-H)thymidine into DNA fragments that are substantially smaller than Okazaki fragments. These small fragments can be chased into DNA of high-molecular-weight, and thus may be precursors in DNA replication, During longer pulses, label also appears in DNA of higher molecular weight, although at an abnormally slow rate. The mutations map at a previously undescribed locus (dnaS) at 72 min on the E. coli chromosome.