FIG. 2.
ScaI restriction maps of the clpX regions of genomic DNA of S. pneumoniae strains EL59, EL873, and EL1392 amplified by PCR with the oligonucleotide primer pair clpX-a and clpX-c (22). Lanes 1 and 7, Gibco 1-kb Plus standard ladder; lane 2, wild-type clpX+ locus from parent strain EL59; lane 3, duplicated spr1426 locus from EL1392, which contains a copy of clpX+ and the clpX<>ermAM cassette; lane 4, Erms revertant of EL1392 containing the wild-type clpX+ region; lane 5, clpX::ermAM with duplicated clpX+ locus from EL873; lane 6, Erms revertant of EL873 containing the wild-type clpX+ region. Shaded arrows, clpX reading frame; hatched arrows, ermAM reading frame; open arrows, genes surrounding clpX (Fig. 1); black dots, ∼0.9 kb of unknown DNA present in EL1392 clpX+ region. ScaI restriction sites are indicated with the letter S and a horizontal line. The break denotes an unknown amount of chromosomal DNA in the EL873 merodiploid. Predicted restriction fragment sizes and indicated DNA standards are in kilobase pairs.
