FIG. 3.

PCR amplification of lytB in Synechocystis PCC6803 using genomic DNA obtained from the wild-type strain and from a mutant with a Kan^r insertion in the NheI site immediately upstream of lytB. The ca. 3.7-kb PCR product from the insertion mutant lytB(NheI)::Kan^r, displayed in the right lane of this 1% agarose gel, is the expected 1.2 kb larger than the wild-type product of about 2.5 kb (middle lane). No trace of the wild-type (i.e., uninterrupted) gene is discernable in the mutant lane. The PCR primers were those used for the initial amplification of lytB and flanking regions (see Fig. 2 and Materials and Methods) and lie outside the BamHI and SmaI sites that define the cloned DNA fragment used to transform Synechocystis. The standards lane (left lane) contains DNA fragments of the indicated sizes.