New Paradigm for Virulence Gene Expression in Pseudomonas plecoglossicida

A team of researchers from the East China University of Science and Technology has identified a new mechanism underlying virulence gene expression in the pathogen Pseudomonas plecoglossicida, which causes severe diseases in various fish, including the large yellow croaker, leading to significant economic losses. The study, published in the journal Microbiological Research, reveals that a cognate two-component system (TCS) comprising histidine kinase PvgS and response regulator PvgA plays a crucial role in regulating the expression of key virulence genes, including the type VI secretion system (T6SS). The researchers demonstrated that the PvgAS system responds to ion-mediated osmolality variations, synergistically affecting T6SS-1 secretion at low osmotic environments and dominating its expression at both high and low temperatures.

Key Takeaways:

• The PvgAS system is a crucial regulator of virulence gene expression in Pseudomonas plecoglossicida, responding to ion-mediated osmolality variations.
• The PvgAS system consists of histidine kinase PvgS and response regulator PvgA, which work together to regulate the expression of key virulence genes, including T6SS-1.
• The PvgAS system exhibits distinct roles of osmolality and temperature in the hierarchical regulatory mechanism to control virulence gene expression.
• The T6SS-1 secretion is synergistically affected by temperature at low osmotic environments, while osmotic pressure dominates its expression at both high and low temperatures.

Statistics:

• 106 genes are directly controlled by PvgA in Pseudomonas plecoglossicida.
• 2-component system PvgAS orchestrates virulence gene expression in response to osmolality in Pseudomonas plecoglossicida.
• 655 base pairs of the DNA sequence are analyzed using Chromatin immuno-precipitation sequencing (ChIP-seq) technology.
• The expression of T6SS-1 is regulated by PvgAS at different osmolality levels, with a response to sodium (Na), potassium (K), and lithium (Li) ions but not sucrose.

Sources:

• The two-component system PvgAS orchestrates virulence gene expression in response to osmolality in Pseudomonas plecoglossicida. Microbiological Research, 2025;302:128358.
• NewsRx. Researchers from East China University of Science and Technology Discuss Findings in Pseudomonas (The two-component system PvgAS orchestrates virulence gene expression in response to osmolality in Pseudomonas plecoglossicida). Life Science Weekly. October 21, 2025; p 6121.