Insertion sequence elements and unique symmetrical genomic regions mediate chromosomal inversions in Streptococcus...

Area of Science:

• Bacterial genomics
• Molecular evolution
• Microbial genetics

Background:

• Chromosomal inversions are common in bacteria, influencing gene expression and adaptation.
• While inversions occur in Streptococcus pyogenes, their frequency and molecular basis are not well understood.

Purpose of the Study:

• To systematically analyze the frequency, locations, and associated molecular markers of chromosomal inversions in Streptococcus pyogenes.
• To establish a framework for characterizing bacterial chromosomal inversions.

Main Methods:

• Analysis of 249 complete Streptococcus pyogenes genomes using a pangenomic core gene synteny framework.
• Identification and cataloging of inversion locations and associated mobile genetic elements.

Main Results:

• 47% of analyzed genomes (118/249) harbored at least one inversion across 23 unique locations.
• Inversions were frequently associated with mobile elements, particularly insertion sequences IS1548 and IS1239 (>80% of cases).
• The most common inversion site (88% of inversions) occurred between conserved rRNA, tRNA, and sigma factor gene regions.

Conclusions:

• Chromosomal inversions are prevalent in Streptococcus pyogenes, with specific insertion sequences and gene regions acting as hotspots.
• Understanding inversion patterns provides insights into bacterial genome plasticity and potential phenotypic changes.
• The developed framework is applicable to studying inversions in other bacterial species.