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Avian pathogenic Escherichia coli T6SS effector protein Hcp2a causes mitochondrial dysfunction through interaction
Liting Lu1, Zhao Qi1, Zhe Chen1
1Anhui Province Key Laboratory of Veterinary Pathobiology and Disease Control, College of Animal Science and Technology, Anhui Agricultural University, Hefei 230036, PR China; Anhui Province Engineering Laboratory for Animal Food Quality and Bio-Safety, College of Animal Science and Technology, Anhui Agricultural University, Hefei 230036, PR China.
Abstract:
The type VI secretion system (T6SS) of avian pathogenic Escherichia coli (APEC) can affect the functions of eukaryotic cells by secreting or injecting effectors. Hemolysin co-regulatory protein (Hcp), one of the markers of the T6SS, is both a structural protein and an effector protein of the T6SS. According to previous studies, mitochondria in eukaryotic cells are targeted by pathogenic bacteria. However, little is known about the regulation of mitochondria in eukaryotic host cells by the T6SS effector protein Hcp of APEC. In our study, DF-1 cells co-incubated with Hcp2a protein for 6 h showed decreased mitochondrial membrane potential, increased Ca2+ concentration, and increased cellular reactive oxygen species (ROS) levels. We therefore conclude that Hcp2a protein causes dysfunction to mitochondria in DF-1 cells. To explain the mechanism that causes mitochondrial dysfunction, we reanalyzed the Hcp2a interaction protein dataset in DF-1 cells, and the Leucine zipper EF-hand-containing transmembrane protein 1 (LETM1), which is associated with mitochondria, was screened. The protein and molecular docking results showed that Hcp2a protein and LETM1 protein have better binding. Finally, subcellular localization results showed that Hcp2a was localized to mitochondria. In summary, Hcp2a effector proteins caused dysfunction to DF-1 cellular mitochondria, and we hypothesize that the interaction of Hcp2a protein with LETM1 protein induces mitochondrial dysfunction and promotes mitochondrial localization of Hcp2a in DF-1 cells.
Insights
Avian pathogenic E. coli
Area of Science:
- Microbiology
- Cell Biology
- Molecular Biology
Background:
- The type VI secretion system (T6SS) in avian pathogenic Escherichia coli (APEC) delivers effector proteins into host eukaryotic cells.
- Mitochondria are known targets of bacterial pathogens, but the specific mechanisms by which APEC T6SS effectors impact mitochondria are not well understood.
- Hemolysin co-regulatory protein (Hcp) is a key T6SS marker and effector protein in APEC.
Purpose of the Study:
- To investigate the effects of the APEC T6SS effector protein Hcp2a on mitochondria in eukaryotic host cells (DF-1 cells).
- To elucidate the molecular mechanism underlying Hcp2a-induced mitochondrial dysfunction.
- To identify host proteins interacting with Hcp2a within DF-1 cells.
Main Methods:
- DF-1 cells were treated with purified Hcp2a protein.
- Mitochondrial function was assessed by measuring membrane potential, intracellular calcium (Ca2+), and reactive oxygen species (ROS) levels.
- Protein-protein interaction analysis, including reanalysis of existing datasets and molecular docking, was performed.
- Subcellular localization of Hcp2a was determined.
Main Results:
- Exposure of DF-1 cells to Hcp2a led to decreased mitochondrial membrane potential, increased Ca2+ concentration, and elevated ROS levels, indicating mitochondrial dysfunction.
- Bioinformatic analysis identified Leucine zipper EF-hand-containing transmembrane protein 1 (LETM1), a mitochondrial protein, as a potential interaction partner for Hcp2a.
- Molecular docking confirmed a favorable binding interaction between Hcp2a and LETM1.
- Subcellular localization studies confirmed that Hcp2a accumulates in the mitochondria of DF-1 cells.
Conclusions:
- The APEC Hcp2a effector protein induces mitochondrial dysfunction in DF-1 cells.
- Hcp2a likely interacts with the mitochondrial protein LETM1, contributing to mitochondrial dysfunction and promoting Hcp2a's localization to mitochondria.
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