Figure 1. Construction of Sweet Janus (SJ) cassette in the cps locus of pneumococcus.

Pentagons represent cassette elements and the dexB and aliA genes flanking the cps locus. Arrows represent oligonucleotides used to amplify fragments of the SJ cassette by PCR (see Table 1 for primer sequences). rpsL* represents the Sm^r mutant rpsL copy in the genomic region outside the Janus or SJ cassette. The PCR products were assembled into the SJ by using Gibson Assembly and the SJ was used to transform the TIGR4S strain to construct the SpnYL001 strain.