FIG. 1.

Structure of (A) the class 1 integron Tn402 and (B) the class 3 integron. The 25-bp inverted repeats are indicated by tall bars labeled IRi and IRt. The 5′ conserved segment (5′-CS) of class 1 and the equivalent region in the class 3 integron are shown as medium lines, with the extent and direction of the intI gene indicated. Each gene cassette is shown as an open box that includes the gene and an adjacent filled box that represents the 59-be. The two parts of the attI sites flanking the cassettes are shown as open bars, and the positions and directions of the P_c promoters are indicated. Parts of the tni module are indicated by thick lines. For Tn402, the transposition genes, tni, and the res site are indicated. (B) The extent of the BamHI fragment of the class 3 integron cloned in pSMB731 and pMAQ481 is shown as a line below, with the positions of some of the restriction enzyme sites. The extent of the sequence in GenBank accession no. D50538 is indicated, and the additional regions sequenced in this work are shown by dashed lines. The fragment present in pRMH808 is shown below. Restriction enzyme sites: B, BamHI; E, EcoRI; H, HindIII; N, NcoI; Sa, SacI; Sm, SmaI.