Mutual exclusivity of hyaluronan and hyaluronidase in invasive group A Streptococcus.
Bottom Line: However, partial encapsulation reduced binding to human complement regulatory protein C4BP, did not enhance survival in whole human blood, and did not increase virulence of WT M4 GAS in a mouse model of systemic infection.Bioinformatics analysis found no hasABC homologs in closely related species, suggesting that this operon was a recent acquisition.These data showcase a mutually exclusive interaction of HA capsule and active HylA among strains of this leading human pathogen.
Affiliation: From the Department of Pediatrics, the School of Chemistry and Molecular Biosciences and Australian Infectious Diseases Research Centre, The University of Queensland, St. Lucia, Queensland 4072, Australia.Show MeSH
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Mentions: HylA is well conserved in closely related genomes including Streptococcus agalactiae, S. pneumoniae, S. suis, and S. aureus suggesting that hylA is unlikely to have been independently acquired by these genomes, but may rather be ancestral among streptococcal species (Fig. 5A; supplemental Table S3). We hypothesize that M1 GAS and other encapsulated serotypes acquired hasABC more recently than hylA, resulting in concurrent HA synthesis and degradation. Preservation of capsule bestows upon GAS resistance to phagocytosis and enhanced survival in vivo, which may have provided selection pressure for inactivating mutations in hylA. Although current data do not exclude that the hylA might be horizontally acquired, the high degree of sequence conservation in HylA proteins among streptococci and other bacterial species (Fig. 5B; supplemental Table S3) suggests that hylA acquisition may have been ancestral to the branching of streptococci. It is possible that hylA is not metabolically essential and that it might be detrimental to certain bacterial products, because a few species have lost this gene (e.g. Streptococcus mutans, Streptococcus uberis, and Streptococcus thermophilus) (supplemental Table S3).
Affiliation: From the Department of Pediatrics, the School of Chemistry and Molecular Biosciences and Australian Infectious Diseases Research Centre, The University of Queensland, St. Lucia, Queensland 4072, Australia.