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Published on: May 23, 2021
Giant Triton Snail Charonia tritonis Macrophage-Expressed Gene 1 Protein Ct-Mpeg1: Molecular Identification,
Wenguang Liu1,2, Bing Liu1,3, Gege Zhang1,3
1CAS Key Laboratory of Tropical Marine Bio-Resources and Ecology, Guangdong Provincial Key Laboratory of Applied Marine Biology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou 510301, China.
Abstract:
Macrophage-expressed gene 1 proteins (Mpeg1/Perforin-2 (PRF2)) are a family of pore-forming proteins (PFPs) which can form pores and destroy the cell membrane of invading pathogens. However, little information is available regarding the function of Mpeg1 in the giant triton snail Charonia tritonis. In this study, a homolog of Mpeg1 (Ct-Mpeg1) was identified in C. tritonis. The predicted protein of Ct-Mpeg1 contains several structural features known in Mpegs, including a membrane attack complex/perforin (MACPF) domain and single transmembrane region. The Ct-Mpeg1 gene was constitutively expressed in almost all tissues examined except in the proboscis, with the highest expression level observed in the mantle. As a typical pore-forming protein, Ct-Mpeg1 has antibacterial activities against Vibrio (including Vibrio alginolyticus and Vibrio parahaemolyticus). In addition, rCt-Mpeg1 challenge to V. alginolyticus represses the expression of most outer membrane protein synthesis-related genes and genes involved in the TCA cycle pathway, which will lead to reduced outer membrane protein synthesis and less energy capacity. This is the first report to characterize the macrophage-expressed gene 1 protein in C. tritonis, and these results suggest that macrophage-expressed gene 1 protein Ct-Mpeg1 is an important immune molecule of C. tritonis that is involved in the bacterial infection resistance of Vibrio, and this study may provide crucial basic data for the understanding of the innate immunity system of C. tritonis.
Insights
The macrophage-expressed gene 1 protein (Ct-Mpeg1) in the giant triton snail provides innate immunity against Vibrio bacteria. This pore-forming protein disrupts bacterial cell membranes and impacts their gene expression and energy production.
Area of Science:
- Marine Biology
- Immunology
- Biochemistry
Background:
- Macrophage-expressed gene 1 proteins (Mpeg1/Perforin-2) are pore-forming proteins crucial for pathogen defense.
- Limited information exists on Mpeg1 function in the giant triton snail, *Charonia tritonis*.
Purpose of the Study:
- To identify and characterize the Mpeg1 homolog (Ct-Mpeg1) in *Charonia tritonis*.
- To investigate the immune function and antibacterial activity of Ct-Mpeg1 against *Vibrio* species.
Main Methods:
- Identification and sequence analysis of *Ct-Mpeg1* gene.
- Gene expression analysis in various *C. tritonis* tissues.
- In vitro antibacterial assays against *Vibrio alginolyticus* and *Vibrio parahaemolyticus*.
- Transcriptomic analysis of *V. alginolyticus* after exposure to recombinant Ct-Mpeg1 (rCt-Mpeg1).
Main Results:
- A *Ct-Mpeg1* homolog was identified in *C. tritonis*, encoding a protein with characteristic Mpeg structural features (MACPF domain, transmembrane region).
- *Ct-Mpeg1* is constitutively expressed across most tissues, with highest levels in the mantle.
- Ct-Mpeg1 exhibits direct antibacterial activity against *Vibrio* species.
- rCt-Mpeg1 challenge significantly repressed genes related to outer membrane protein synthesis and the TCA cycle in *V. alginolyticus*, impairing bacterial defense and energy metabolism.
Conclusions:
- Ct-Mpeg1 is a key immune molecule in *Charonia tritonis*, contributing to innate immunity against *Vibrio* infections.
- Ct-Mpeg1 functions as a pore-forming protein that compromises bacterial membrane integrity and metabolic pathways.
- This study provides foundational data for understanding the innate immune system of *C. tritonis*.
