A novel aquaporin Aagp contributes to <i>Streptococcus suis</i> H₂O₂ efflux and virulence

<i>Streptococcus suis</i> is a bacterium that can cause infections in pigs and humans. Although oxidative stress is common occurrence during bacterial growth and infection, the regulation networks of <i>S. suis</i> under oxidative stress remain poorly understood. To address this, we utilized RNA-Seq to reveal the transcriptional landscape of <i>S. suis</i> in response to H₂O₂ stress. We identified novel genes responsible for <i>S. suis</i> resistance to oxidative stress, including those involved in DNA repair or protection, and essential for the biosynthesis of amino acids and nucleic acids. In addition, we found that a novel aquaporin, Aagp, belonging to atypical aquaglyceroporins and widely distributed in diverse <i>S. suis</i> serotypes, plays a crucial role during H₂O₂ stress. By performing oxidative stress assays and measuring the intracellular H₂O₂ concentrations of the wild-type strain and <i>Aagp</i> mutants during H₂O₂ stress, we found that Aagp facilitated H₂O₂ efflux. Additionally, we found that Aagp might be involved in glycerol transport, as shown by the growth inhibition and H₂O₂ production in the presence of glycerol. Mice infection experiments indicated that Aagp contributed to <i>S. suis</i> virulence. This study contributes to understanding the mechanism of <i>S. suis</i> oxidative stress response, <i>S. suis</i> pathogenesis, and the function of aquaporins in prokaryotes.