Molecular structure of the replication origin of a Bacillus amyloliquefaciens plasmid pFTB14.

The structure of a 1.5-kb DNA sequence that is necessary and sufficient for the replication of an 8.2-kb cryptic plasmid, pFTB14, isolated from a strain of Bacillus amyloliquefaciens has been characterized. The 1.5-kb DNA sequence contains an open reading frame, rep, stretching for 1017 bp, a promoter region for rep expression, and a possible replication origin for the plasmid upstream of the promoter. The rep product is trans-active and essential for plasmid replication. The predicted rep protein is a basic protein, as are the RepC protein of pT181, RepB of pUB110 and protein A of pC194 (all these found in staphylococci) and the pi protein of the R6K plasmid of Escherichia coli. The predicted rep protein has highly homologous amino acid sequences with protein A of pC194 and RepB of pUB110 throughout the protein molecule, but not with RepC of pT181, pi of R6K or protein RepH encoded by and initiating the replication of pC194.