Figure 6.

Spontaneous excision of M1 S. pyogenes SF370. Mitogenic exotoxin Z (smeZ/spy1998) and putative PTS system enzyme IIC component (spy2050) are the two coding genes where the boundaries for the natural isolate of M-protein-negative group A streptococcus T11 can be found (T11 deletion). In two out of four individual cycled cultures, an amplicon compatible with the excision of most part of the 47-kb SSR element was detected as shown by the two deletions (deletion 1 and deletion 2). Both amplicons were 200 bp apart from the boundaries of the natural T11 isolates. The region defined by the TA skew analysis starts 4520 bp upstream of the 5'-end of smeZ, and ends 835 bp downstream of the 3' end of spy2050 (see additional file 1). Oligonucleotides SVC1-1, SVC1-2, SVC2-3, SVC2-4 are represented above the genes. A 0.5-kb scale is indicated.