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Invasive Acinetobacter baumannii ABC141 strain relies on the twin-arginine translocation export system for adhesion

Charline Debruyne1,2, Landon Hodge1, Karsten Hokamp3

  • 1Department of Pathobiological Sciences, School of Veterinary Medicine, University of Wisconsin-Madison, Madison, WI, USA.

Microbiology (Reading, England)
|December 9, 2025
PubMed

Insights

Acinetobacter baumannii efficiently invades host cells during its exponential growth phase. The twin-arginine translocation (Tat) export system is crucial for bacterial adhesion, but not invasion or intracellular multiplication, revealing a novel role in pathogenesis.

Area of Science:

  • Microbiology
  • Infectious Diseases
  • Bacterial Pathogenesis

Background:

  • Acinetobacter baumannii causes severe, multi-drug-resistant hospital-acquired infections.
  • Clinical isolates can invade and multiply within eukaryotic host cells.
  • Previous work showed strain ABC141 invades and multiplies intracellularly without causing cytotoxicity.

Purpose of the Study:

  • To investigate the growth phase-dependent characteristics of A. baumannii intracellular survival.
  • To identify gene expression changes associated with intracellular lifestyle.
  • To elucidate the role of the twin-arginine translocation (Tat) export system in A. baumannii pathogenesis.

Main Methods:

  • Transcriptomic comparison of exponentially and stationary phase A. baumannii ABC141 cultures.
  • Analysis of a tatABC operon mutant strain.
  • Assessment of bacterial adhesion, invasion, and intracellular multiplication in host cells.

Main Results:

  • Bacterial adhesion, invasion, and intracellular multiplication are most efficient in the exponential growth phase.
  • The twin-arginine translocation (Tat) export system is upregulated in exponentially grown cells.
  • A tatABC mutant showed impaired adhesion but retained invasion and intracellular multiplication capabilities.

Conclusions:

  • Bacterial growth phase significantly influences the ability of A. baumannii to interact with host cells.
  • The Tat export system plays a previously unrecognized role in A. baumannii adhesion to host cells.
  • These findings offer new insights into the pathogenesis of A. baumannii infections.
Keywords:
ABC141Acinetobacter baumanniiadhesiontwin-arginine translocation (Tat) system

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