Distribution of Type I Restriction–Modification Systems in Streptococcus suis: An Outlook

Abstract

<i>Streptococcus suis</i> is a porcine commensal and pathogen with zoonotic potential. We recently identified a novel Type I restriction-modification (R-M) system in a zoonotic <i>S. suis</i> clone which has emerged in the Netherlands. Here, we describe the DNA inversions in the specificity subunit of this system in <i>S. suis</i> serotype 2, clonal complex 20 and explain the absence of domain movement by the absence of repeats. In addition, we identified a core Type I R-M system present in 95% of the isolates and found an association of the distribution of Type I R-M systems in the <i>S. suis</i> genome with population structure. We speculate on the potential role of Type I R-M systems in <i>S. suis</i> given the recently described associations of Type I R-M systems with virulence and propose future research directions.