Fig 7. Location of tranposons in an L. interrogans sph2 mutant and in sph2 complemented isolates.

A. Genetic organization of L. interrogans sph1-sph2 locus. The location of the transposon insertion in the sph2 mutant is designated with "Tn." The ends of the sequence cloned for complementation studies are marked with dashed lines. The segment of sph2 encoding the enzymatic domain is shaded gray, and the catalytic residues demonstrated experimentally to be necessary for Bacillus subtilis sphingomyelinase activity are abbreviated by their single-letter amino acid codes. B. Genetic structure of the complementing transposon. The sph2 sequences were cloned between the KpnI and XhoI restriction sites in the transposon. The aadA gene encodes resistance to spectinomycin. C. Insertion sites of the complementing transposon. The location of the complementing transposon in four transconjugants (TC) is indicated by the vertical line. The arrow above the vertical line depicts the orientation of the sph2 gene in the transposon. The dashed open arrow indicates a pseudogene. HP, hypothetical protein.