| Popis: |
We have shown that the Bgl II to Bam HI (79·6% to 95·8%) region of the coliphage 186 chromosome can direct 186-specific replication. DNA sequencing of the region revealed five presumptive genes, CP80, CP81, CP83, CP84 and CP87 . Surprisingly, alleles of the previously defined replication gene, A , were localized in both CP84 and CP87 . We have successfully constructed a 186 minichromosome using the single gene CP87 , and determined that CP84 was not concerned with replication, neither of a minichromosome nor of the phage. Rather, the replication defect seen with amber mutants of CP84 reflects a polarity effect on the downstream expression of CP87 . We have concluded that CP87 is the only phage gene necessary for 186 replication, and have called it gene A . |
