NYMC Faculty Publications

Recombinational Exchange of M-Fibril and T-Pilus Genes Generates Extensive Cell Surface Diversity in the Global Group a Streptococcus Population

Author Type(s)

Faculty, Resident/Fellow

DOI

10.1128/mbio.00693-24

Journal Title

Mbio

Document Type

Article

Publication Date

5-1-2024

Department

Pathology, Microbiology and Immunology

Keywords

cell surface proteins, genotyping, group A streptococcus, molecular epidemiology, pili, population biology

Disciplines

Medicine and Health Sciences

Abstract

Among genes present in all group A streptococci (GAS), those encoding M-fibril and T-pilus proteins display the highest levels of sequence diversity, giving rise to the two primary serological typing schemes historically used to define strain. A new genotyping scheme for the pilin adhesin and backbone genes is developed and, when combined with emm typing, provides an account of the global GAS strain population. Cluster analysis based on nucleotide sequence similarity assigns most T-serotypes to discrete pilin backbone sequence clusters, yet the established T-types correspond to only half the clusters. The major pilin adhesin and backbone sequence clusters yield 98 unique combinations, defined as “pilin types.” Numerous horizontal transfer events that involve pilin or emm genes generate extensive antigenic and functional diversity on the bacterial cell surface and lead to the emergence of new strains. Inferred pilin genotypes applied to a meta-analysis of global population-based collections of pharyngitis and impetigo isolates reveal highly significant associations between pilin genotypes and GAS infection at distinct ecological niches, consistent with a role for pilin gene products in adaptive evolution. Integration of emm and pilin typing into open-access online tools (pubmlst.org) ensures broad utility for end-users wanting to determine the architecture of M-fibril and T-pilus genes from genome assemblies.

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