FIG. 3.

Nucleotide sequences of the oriT region of the pHT plasmid. The 420-bp noncoding DNA sequence region between ORF31 and ORF32 is shown. The horizontal arrows under the sequences indicate the direct repeats (DR-a, DR-b, and DR-c) and inverted repeats (IR5S and IR5L) in the oriT region. The names and locations of oligonucleotide primers used for the analysis of the oriT region are shown on the sequence with the angled arrows. Two downward arrowheads on the complementary sequence show the possible nick sites in the oriT region based on the sequence comparisons with other defined nick sites (see the text and Fig. 5). The vertical arrows that are numbered as 323 and 327 indicate the locations of the two Tn917-lac insertion mutants of pHTβ that abolished transfer ability. The putative promoter region (−35 and −10) and ribosome binding site (Shine-Dalgarno sequence [S.D.]) for ORF32 are shown upstream of the start codon. The asterisk marks indicate the dyad symmetric sequences overlapping the promoter region.