Genome mining reveals the prevalence and extensive diversity of toxin-antitoxin systems in Staphylococcus aureus.

Abstract

Staphylococcus aureus (S. aureus) is a highly pathogenic and adaptable Gram-positive bacterium that exhibits persistence in various environments. The toxin-antitoxin (TA) system plays a crucial role in the defense mechanism of bacterial pathogens, allowing them to survive in stressful conditions. While TA systems in clinical pathogens have been extensively studied, there is limited knowledge regarding the diversity and evolutionary complexities of TA systems in S. aureus. We conducted a comprehensive in silico survey using 621 publicly available S. aureus isolates. We employed bioinformatic search and prediction tools, including SLING, TADB2.0, and TASmania, to identify TA systems within the genomes of S. aureus. Our analysis revealed a median of seven TA systems per genome, with three type II TA groups (HD, HD_3, and YoeB) being present in over 80% of the strains. Additionally, we observed that TA genes were predominantly encoded in the chromosomal DNA, with some TA systems also found within the Staphylococcal Cassette Chromosomal mec (SCCmec) genomic islands. This study provides a comprehensive overview of the diversity and prevalence of TA systems in S. aureus. The findings enhance our understanding of these putative TA genes and their potential implications in S. aureus ecology and disease management. Moreover, this knowledge could guide the development of novel antimicrobial strategies.