Exogenous glycogen utilization effects the transcriptome and pathogenicity of Streptococcus suis serotype 2

Area of Science:

• Microbiology
• Pathogenomics
• Bacterial Metabolism

Background:

• Streptococcus suis serotype 2 (SS2) is a significant zoonotic pathogen impacting human and swine health.
• Bacterial pathogens require efficient nutrient acquisition, like carbon sources, for host survival and proliferation.
• The role of glycogen utilization in SS2 pathogenesis and host adaptation remains largely unexplored.

Purpose of the Study:

• To investigate the impact of exogenous glycogen on SS2 gene expression and virulence.
• To elucidate the mechanism of glycogen utilization by SS2 and its contribution to pathogenicity.

Main Methods:

• Transcriptome sequencing (RNA-Seq) was employed to analyze SS2 gene expression in response to glycogen.
• A mutant strain (ΔapuA) lacking the amylopullulanase gene (apuA) was generated for comparative pathogenicity studies.
• Pathogenicity assays, including hemolytic activity, adhesion, invasion, and lethality, were performed.

Main Results:

• Glycogen induction significantly altered SS2's core carbon metabolism, promoting the pentose phosphate pathway and carbohydrate transport while perturbing glycolysis and the citrate cycle.
• Extracellular glycogen utilization enhanced SS2's hemolytic activity, adhesion, invasion capabilities, and overall lethality.
• Deletion of apuA impaired SS2's pathogenicity, even when grown on glucose, highlighting ApuA as a crucial virulence factor.

Conclusions:

• Exogenous glycogen utilization profoundly influences the SS2 genome's expression profile, promoting carbon adaptation and enhancing pathogenicity.
• The amylopullulanase ApuA is essential for SS2's ability to utilize glycogen and contributes significantly to its virulence.
• Targeting glycogen utilization pathways presents a potential strategy for controlling SS2 infections.