Fig. 1

Diagnostic PCR of wild-type (WT), deletion (∆) and insertion (S1–S3) strains for smp1–smp4. PCR was performed using the primers listed in Additional file 1, Table S2. Molecular weight standard sizes (kb) are shown to the left. Predicted product sizes for wild-type and deletion strains are shown to the right of each gel. The asterisk for smp4 indicates primer dimers. See text for further details