Regulation of Type VI Secretion Systems of Burkholderia during transition to intracellular lifestyle.

Burkholderia thailandensis switches from T6SS-1 to T6SS-5 during phagosomal maturation, with T6SS-1 assembly declining as T6SS-5 expression increases.

• Why it matters: Understanding how pathogenic bacteria regulate their secretion systems during host infection can reveal mechanisms of immune evasion and intracellular survival, which are critical for developing targeted therapies.
• What they did: The study examined gene expression and assembly of T6SSs in B. thailandensis, using deletion mutants of virA and T6SS-5 membrane complex, to analyze their roles during host cell invasion and intracellular transition.
• The result: T6SS-1 activity induces mitochondrial fragmentation and apoptosis in host cells, but its silencing via T6SS-5 expression suggests a bacterial strategy to preserve its replicative niche during infection.