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Putative type VI secretion systems of Vibrio parahaemolyticus contribute to adhesion to cultured cell monolayers

Ying Yu1, Hong Yang, Jun Li

  • 1Zhejiang Provincial Key Laboratory of Preventive Veterinary Medicine, Institute of Preventive Veterinary Medicine, Zhejiang University, 388 Yuhangtang Road, Hangzhou 310058, China.

Archives of Microbiology
|April 27, 2012
PubMed

Insights

Vibrio parahaemolyticus utilizes two type VI secretion systems (T6SS) for host cell adhesion. While vpT6SS1 aids bacterial adhesion, vpT6SS2, with Hcp2 as a translocon, shows differential effects on adhesion to various cell lines.

Area of Science:

  • Microbiology
  • Molecular Biology
  • Genomics

Background:

  • Vibrio parahaemolyticus is a significant foodborne pathogen.
  • Type VI secretion systems (T6SS) are crucial for bacterial virulence and host interactions.
  • The presence and function of T6SS in V. parahaemolyticus are not fully elucidated.

Purpose of the Study:

  • To investigate the role of two putative T6SS clusters (vpT6SS1 and vpT6SS2) in the adhesion of Vibrio parahaemolyticus to host cells.
  • To characterize the components and functions of these vpT6SS systems.

Main Methods:

  • Genome sequence analysis to identify T6SS genes (icmF1, icmF2, hcp1, hcp2).
  • Construction and analysis of gene deletion mutants (ΔicmF1, Δhcp1, ΔicmF2, Δhcp2).
  • Bacterial adhesion assays using Caco-2 and HeLa cell lines.
  • Western blot analysis to detect Hcp proteins.
  • Quantitative PCR to assess gene transcript levels.

Main Results:

  • Vibrio parahaemolyticus possesses two IcmF family genes (icmF1, icmF2) in T6SS clusters.
  • icmF1 is more prevalent in clinical isolates, while icmF2 is found in all strains.
  • Deletion mutants ΔicmF1 and Δhcp1 significantly reduced adhesion to Caco-2 and HeLa cells.
  • Mutants ΔicmF2 and Δhcp2 showed reduced adhesion only to HeLa cells.
  • Hcp2 was identified as a translocon for T6SS2.
  • Lower transcript levels of hcp1 and icmF1 compared to hcp2 and icmF2 were observed.

Conclusions:

  • Both vpT6SS1 and vpT6SS2 contribute to the adhesion of Vibrio parahaemolyticus to host cells.
  • vpT6SS1 plays a significant role in bacterial adhesion, although its translocon (Hcp1) was not detected.
  • vpT6SS2, with Hcp2 as a translocon, also contributes to adhesion, particularly to HeLa cells.
  • Differential expression and distribution of vpT6SS components suggest distinct roles in V. parahaemolyticus pathogenesis.

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