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CorA2-mediated magnesium transport is essential for stress adaptation and virulence of Streptococcus agalactiae

Jiayi Liu1, Fengyang Li1, Yong-An Zhang2,3

  • 1Hubei Hongshan Laboratory, College of Fisheries, Huazhong Agricultural University, Wuhan, 430070, China.

Veterinary Research
|April 22, 2026
PubMed

Insights

Magnesium transporter CorA2 is essential for Streptococcus agalactiae survival and virulence. Disrupting CorA2 impairs bacterial growth and resistance to host defenses, making it a potential target for new anti-infective strategies.

Area of Science:

  • Microbiology
  • Molecular Biology
  • Pathogenesis

Background:

  • Magnesium (Mg2+) homeostasis is vital for bacterial survival and virulence.
  • Streptococcus agalactiae is a significant pathogen in fish and mammals, but its Mg2+ uptake mechanisms are unknown.

Purpose of the Study:

  • To identify and characterize the Mg2+ transporter in Streptococcus agalactiae.
  • To investigate the role of this transporter in bacterial virulence and host-pathogen interactions.

Main Methods:

  • Genetic analysis using a corA2 deletion mutant (ΔcorA2) and structure-guided point mutants.
  • Biochemical assays to assess Mg2+ uptake and bacterial growth under stress conditions.
  • In vitro assays for phagocytosis resistance, macrophage survival, host cell adhesion/invasion, and in vivo tilapia infection model.

Main Results:

  • CorA2 was identified as an essential Mg2+ transporter in S. agalactiae HN016.
  • ΔcorA2 mutants showed impaired growth under Mg2+ limitation and increased susceptibility to host-mimicking stresses.
  • The mutant was less resistant to phagocytosis and macrophage survival but showed enhanced adhesion and invasion.
  • In vivo, the ΔcorA2 strain was significantly attenuated in a tilapia infection model, with reduced mortality and bacterial burden.

Conclusions:

  • CorA2-mediated magnesium homeostasis is crucial for S. agalactiae virulence.
  • This transporter is essential for overcoming host immune defenses and establishing systemic infections.
  • CorA2 represents a promising target for developing novel anti-infective therapies against S. agalactiae.
Keywords:
Streptococcus agalactiaeCorA2magnesium transporttilapiavirulence

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