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Function of Burkholderia pseudomallei RpoS and RpoN2 in bacterial invasion, intracellular survival, and

Duong Thi Hong Diep1,2, Long Binh Vong3,4, Sumalee Tungpradabkul5

  • 1Department of Biochemistry, Faculty of Medicine, University of Medicine and Pharmacy at Ho Chi Minh City, Ho Chi Minh City, Vietnam. duongthihongdiep@ump.edu.vn.

Antonie Van Leeuwenhoek
|February 23, 2024
PubMed

Insights

Burkholderia pseudomallei sigma S (RpoS) and RpoN2 are crucial for bacterial invasion and intracellular survival. These factors influence multinucleated giant cell formation and type III secretion system regulation in host cells.

Area of Science:

  • Microbiology
  • Infectious Diseases
  • Bacterial Pathogenesis

Background:

  • Melioidosis, caused by Burkholderia pseudomallei (B. pseudomallei), is a high-mortality disease in tropical regions.
  • The sigma S (RpoS) transcription factor in B. pseudomallei is known for its role in stationary phase survival and oxidative stress resistance.
  • Bioinformatic analysis revealed two rpoN genes (rpoN1 and rpoN2) in the B. pseudomallei genome.

Purpose of the Study:

  • To investigate the involvement of B. pseudomallei RpoS and RpoN2 in bacterial invasion and intracellular survival.
  • To determine the role of these factors in the formation of multinucleated giant cells (MNGCs) in infected macrophages.
  • To elucidate the regulation of the type III secretion system and bipB-bipC gene expression by RpoS and RpoN2.

Main Methods:

  • Utilized the mouse macrophage cell line RAW264.7 as a model for B. pseudomallei infection.
  • Assessed bacterial invasion and intracellular survival rates.
  • Quantified MNGC formation in infected RAW264.7 cells.
  • Analyzed the expression of bipB-bipC genes in relation to RpoS and RpoN2 activity.

Main Results:

  • MNGC formation in RAW264.7 cells was dependent on a minimum intracellular bacterial load (≥5 × 10⁴).
  • Similar MNGC formation (15%) was observed with wild-type B. pseudomallei (MOI 2) and RpoN2 or RpoS mutants at higher MOIs (10 and 100, respectively).
  • Demonstrated the regulatory role of RpoS and RpoN2 in the type III secretion system, specifically on bipB-bipC gene expression.

Conclusions:

  • B. pseudomallei RpoS and RpoN2 play significant roles in the early stages of infection, including invasion and intracellular survival.
  • These transcription factors are involved in modulating host cell responses, such as MNGC formation.
  • RpoS and RpoN2 are regulators of the type III secretion system, impacting virulence factor expression in B. pseudomallei.
Keywords:
Burkholderia pseudomalleiMultinucleated giant cell formationRpoN2RpoSType III secretion system

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