Volume 25, Number 8—August 2019
Dispatch
Emergent Invasive Group A Streptococcus dysgalactiae subsp. equisimilis, United States, 2015–2018
Figure 2
![Ancestral recombination event depicting Streptococcus pyogenes group A carbohydrate gene donor (GAS/SP-5005; GenBank accession no. NC007297), group C S. dysgalactiae subsp. equisimilis recipient (GCS/SE7136; GenBank accession no. NCTC7136), and progeny group A S. dysgalactiae subsp. equisimilis progeny (GAS/SE/ST128) described in study of emergent invasive group A Streptococcus dysgalactiae subspecies equisimilis, United States, 2015–2018 . The deduced crossover points between the group A gene c](/eid/images/18-1758-F2.jpg)
Figure 2. Ancestral recombination event depicting Streptococcus pyogenes group A carbohydrate gene donor (GAS/SP-5005; GenBank accession no. NC007297), group C S. dysgalactiae subsp. equisimilis recipient (GCS/SE7136; GenBank accession no. NCTC7136), and progeny group A S. dysgalactiae subsp. equisimilis progeny (GAS/SE/ST128) described in study of emergent invasive group A Streptococcus dysgalactiae subspecies equisimilis, United States, 2015–2018. The deduced crossover points between the group A gene cluster (red) donor and group C (green) recipient strains are shown. The 3 genes required for inclusion of the immunodominant N-acetylglucosamine side chain within the group A carbohydrate (gacI, gacJ, and gacK) are shown in red. The coordinates of the fragment transferred that is highly conserved between the donor and the progeny are indicated. The length of the 3 genomic regions are indicated. The gacE/gccE and ebsA genes are shown as green/red hybrids. The extra gcc cluster genes not conserved within the gac cluster are shown in blue. The relative sequence identities of the 3 different regions of progeny (bottom) gac cluster genes with the group A S. pyogenes donor (top) and group C S. equisimilis recipient (middle) are indicated. The middle segment (asterisk) indicates a range of 56%–77% sequence identity between each of the 8 structural genes (gacF–pepT) that were received intact from the S. pyogenes donor. The gac cluster genes are described in more detail in van Sorge et al. (1). Gene assignments are as follows: dnaG, DNA primase; rpoD, major RNA polymerase sigma factor; mscF, metal sulfur complex assembly factor; gacA-L, group A carbohydrate biosynthetic genes (putative functions described in van Sorge et al. [1]); gccA-N, group C carbohydrate biosynthetic genes. gccA-L are functional homologs of gacA-L. gccM and gccN putatively encode an additional glycosyl transferase and UDP-monosaccharide 4-epimerase, respectively; ebsA, pore-forming protein; fd, ferredoxin (complement strand); ctlK, cytidylate kinase; infC, translation initiation factor IF-3.
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