To be capsulated or not be capsulated: that is the GAS question
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To the Editor,
The capsule of Streptococcus pyogenes (Group A Streptococcus, GAS) is composed by hyaluronic acid, the same component of the extracellular matrix of higher animals, humans included. Its synthesis as a linear polymer of N-acetylglucosamine and glucuronic acid is mediated by three enzymes whose genes (hasA, hasB, and hasC) are clustered in an operon [1, 2].
The most relevant is hasA gene, encoding a membrane-associated enzyme, hyaluronan synthase, that promotes the formation of the hyaluronic acid polymer from the nucleotide sugar precursors. The hasA gene is 1260 nucleotides long, coding for a 420 aminoacids protein. According to transcriptional studies , the start codon is a GTG triplet; nevertheless, many nucleotide entries identified in-frame ATG as the first codon, either upstream or downstream the GTG triplet, reporting longer or shorter deduced aminoacid sequences.
The hasABC operon is conserved among GAS strains but it is known that there are capsule-negative emm...
- 1.Wessels MR (2016) Cell wall and surface molecules: capsule. In: Ferretti JJ, Stevens DL, Fischetti VA (eds) Streptococcus pyogenes : basic biology to clinical manifestations [internet]. University of Oklahoma Health Sciences Center, Oklahoma City (OK) Available from http://www.ncbi.nlm.nih.gov/books/NBK333410/ Google Scholar
- 2.Wessels MR (2019) Capsular polysaccharide of group a Streptococcus. Microbiol Spectr 7:1. https://doi.org/10.1128/microbiolspec.GPP3-0050-2018 CrossRefGoogle Scholar
- 6.Efstratiou A, Sriskandan S (2015) Emergence of a new highly successful acapsular group A Streptococcus clade of genotype emm89 in the United Kingdom. MBio 6:e00622Google Scholar
- 7.Flores AR, Chase McNeil J, Shah B, Van Beneden C, Shelburne SA 3rd (2018) Capsule-negative emm types are an increasing cause of pediatric group a streptococcal infections at a large pediatric hospital in Texas. J Pediatric Infect Dis Soc 1. https://doi.org/10.1093/jpids/piy053
- 12.Dale JB, Washburn RG, Marques MB, Wessels MR (1996) Hyaluronate capsule and surface M protein in resistance to opsonization of group A streptococci. Infect Immun 64:1495–1501Google Scholar
- 14.van de Rijn I (1983) Streptococcal hyaluronic acid: proposed mechanisms of degradation and loss of synthesis during stationary phase. J Bacteriol 156:1059–1065Google Scholar
- 22.Bernard PE, Kachroo P, Eraso JM et al (2019) Polymorphisms in RocA Contribute to the Molecular Pathogenesis of Serotype M28 Group A Streptococcus. Am J Pathol. https://doi.org/10.1016/j.ajpath.2019.06.009
- 24.Matysik A, Kline KA (2019) Streptococcus pyogenes capsule promotes microcolony-independent biofilm formation. J Bacteriol. https://doi.org/10.1128/JB.00052-19