FIG.3.

(A) Structural organization of the ori region of pRV500. Coordinates of the schematized fragment are indicated at each end. The percentage of A-T composition of particular segments is indicated, and −35 and −10 boxes of the putative promoter of repA are represented. Each unit of identified direct (DR) or inverted (IR) repeats is depicted by an arrow. The sequence of the repeat units is indicated below. Lowercase letters give alternative sequence found in one of the units. Underlined letters indicate the nucleotides conserved in the iterons of pEF418 (AF408195) and pUCL287 (X75607). The motif TTGTCTGTTTAT, obtained by the juxtaposition of the repeated units, was also found to be present in the iterons of pMD5057 (AF440277), pLKS (AB035265), pRC18 (AF200347), and pLA105 (D49554) but not in those of pLA103 (D55703) or pSK639 (U40259). (B) Conservation of an N-terminal-to-central region in Rep proteins of three subfamilies of class A theta plasmids. Numbers at the left and at the right of the alignment indicate the coordinates of the first and last residues shown, respectively. The total number of residues for each protein is given in parentheses. Residue shading is as described in the legend for Fig. 2. Respective database accession numbers for pUCL287 to pPS10, in the order shown in the figure, are Q51863, P95741, Q47808, Q9S0J9, Q52180, Q07137, Q48681, P22308, and Q52546.