PHYSICAL MAPPING OF THE ORIGINS OF REPLICATION OF BACILLUS SUBTILIS BACTERIOPHAGE SP01
Doctor of Philosophy
The DNA of Bacillus subtilis bacteriophage SP01 is a linear duplex 140 kilobasepairs long, with direct terminal repeats of 12.4 kilobasepairs. It contains the unusual base 5-hydroxymethyluracil in place of thymine. Southern transfer hybridization analysis of pulse-labeled early replicating intermediates was used to localize the origins of replication on the physical map of SP01. The fragments that were consistently detected in this manner correspond to a region of the DNA extending from the middle of the left terminal repeat to about 32 kilobasepairs from the left end of the genome. Thus there is at least one origin of replication between the middle of the left terminal repeat and a point about 32 kilobasepairs from the left end of the genome. However, because of the nature of the terminal repeats and the ambiguity of the restriction maps of this region, as many as three origins of replication may be indicated: one in each direct terminal repeat and one about 30-32 kilobasepairs from the left end of the genome, in the vicinity of Xba I fragment 16b.