FIG. 1.

Construction strategy used for urease-negative mutants of Y. enterocolitica serotypes O:3 and O:8. The linearized restriction map of plasmid p19kd-107 is shown at the top. DNAs from different origins are indicated by different types of lines. The open bars indicate pBR322 DNA, medium-thick lines indicate Y. enterocolitica genomic DNA, thick lines indicate the suicide vector pRV1 DNA, and the open trapezoids indicate Km-GB DNA. Part of the genomic fragment cloned into the BamHI site of pBR322 has been sequenced (25), and the location of the 2,680-bp nucleotide sequence (accession no. Z18865) is shown by the thin line under the p19kd-107 map. The yeuABC genes are indicated by open arrows and the letters A, B, and C, respectively, and truncated forms of the genes are indicated by ′A and C′. Restriction endonuclease recognition sites are indicated above the maps, and the following abbreviations are used: C, ClaI; E, EcoRI; Ev, EcoRV; Sa, Sau3AI (only one site of many is indicated); Sc, ScaI; Sp, SphI; St, StyI; X, XhoI. The antibiotic resistance(s) mediated by each construct is indicated in parentheses on the right. The approximate locations of the crossovers between the pPL3 and the Y. enterocolitica serotype O:3 and O:8 genomic DNAs are indicated by crossed lines. The oligonucleotide primers used for PCRs and sequencing are indicated by the arrows and numbers under the genomic maps at the bottom.