Figure 1.

Physical map of replication and better-than-random segregation genes of plasmid pDB101. (A) pDB101 has extraordinarily long inverted repeated sequences that comprise about 76% of the plasmid molecule (10). The single-copy DNA is indicated as a broken line. The duplicated sequences are denoted by a continuous line, and by double coordinates. The promoters (Pcop, Prep, PIII, Pδ, Pω, and Pɛ) and the plasmid replication origin (ori) are denoted by filled and empty boxes, respectively. RNA transcripts are indicated by thin arrows, and the gene products (copS, repS, δ, ω, ɛ, and ζ) are denoted by thick arrows. The filled arrows denote previously identified products and the open arrow, the product identified in this work. The SegB region is indicated. (B) Nucleotide sequence of the Pcop (Pcop1-Pcop2), Pδ, and Pω promoters. The transcription start sites of Pcop1, Pcop2, and Pδ and Pω, determined by primer extension assays, are denoted by bent arrows. Conserved −35 and −10 regions are indicated as open boxes. The coordinates are indicated. The heptamers and their relative orientation are indicated by thin arrows below the nucleotide sequence.