Related Experiment Video
Updated: Apr 29, 2026
Author Spotlight: Scalable Drug Screening Protocol for Efficient Discovery of M. abscessus Treatments
Published on: October 25, 2024
Antibacterial activity and immune responses of a molluscan macrophage expressed gene-1 from disk abalone, Haliotis
S D N K Bathige1, Navaneethaiyer Umasuthan1, Ilson Whang1
1Department of Marine Life Sciences, School of Marine Biomedical Sciences, Jeju National University, Jeju Self-Governing Province 690-756, Republic of Korea; Fish Vaccine Research Center, Jeju National University, Jeju Special Self-Governing Province 690-756, Republic of Korea.
Abstract:
The membrane-attack complex/perforin (MACPF) domain-containing proteins play an important role in the innate immune response against invading microbial pathogens. In the current study, a member of the MACPF domain-containing proteins, macrophage expressed gene-1 (MPEG1) encoding 730 amino acids with the theoretical molecular mass of 79.6 kDa and an isoelectric point (pI) of 6.49 was characterized from disk abalone Haliotis discus discus (AbMPEG1). We found that the characteristic MACPF domain (Val(131)-Tyr(348)) and transmembrane segment (Ala(669)-Ile(691)) of AbMPEG1 are located in the N- and C-terminal ends of the protein, respectively. Ortholog comparison revealed that AbMPEG1 has the highest sequence identity with its pink abalone counterpart, while sequences identities of greater than 90% were observed with MPEG1 members from other abalone species. Likewise, the furin cleavage site KRRRK was highly conserved in all abalone species, but not in other species investigated. We identified an intron-less genomic sequence within disk abalone AbMPEG1, which was similar to other mammalian, avian, and reptilian counterparts. Transcription factor binding sites, which are important for immune responses, were identified in the 5'-flanking region of AbMPEG1. qPCR revealed AbMPEG1 transcripts are present in every tissues examined, with the highest expression level occurring in mantle tissue. Significant up-regulation of AbMPEG1 transcript levels was observed in hemocytes and gill tissues following challenges with pathogens (Vibrio parahemolyticus, Listeria monocytogenes and viral hemorrhagic septicemia virus) as well as pathogen-associated molecular patterns (PAMPs: lipopolysaccharides and poly I:C immunostimulant). Finally, the antibacterial activity of the MACPF domain was characterized against Gram-negative and -positive bacteria using a recombinant peptide. Taken together, these results indicate that the biological significance of the AbMPEG1 gene includes a role in protecting disk abalone through the ability of AbMPEG1 to initiate an innate immune response upon pathogen invasion.
Insights
The macrophage expressed gene-1 (MPEG1) in disk abalone initiates innate immunity against pathogens. This study characterizes AbMPEG1, revealing its role in immune defense and antibacterial activity.
Area of Science:
- Invertebrate immunology
- Marine biology
- Molecular biology
Background:
- Membrane-attack complex/perforin (MACPF) domain proteins are crucial for innate immunity against microbial pathogens.
- Macrophage expressed gene-1 (MPEG1) is a key MACPF protein involved in immune responses.
Purpose of the Study:
- To characterize the disk abalone MPEG1 (AbMPEG1) gene and protein.
- To investigate the role of AbMPEG1 in the innate immune response of disk abalone.
Main Methods:
- Bioinformatic analysis for domain identification and ortholog comparison.
- Genomic sequence analysis and identification of transcription factor binding sites.
- Quantitative PCR (qPCR) for gene expression analysis in various tissues and after pathogen challenge.
- Characterization of antibacterial activity using a recombinant AbMPEG1 peptide.
Main Results:
- AbMPEG1 possesses a characteristic MACPF domain and a transmembrane segment.
- High sequence identity was observed with MPEG1 from other abalone species, with a conserved furin cleavage site.
- AbMPEG1 transcripts were detected in all examined tissues, with highest expression in mantle.
- Pathogen and PAMP challenges significantly upregulated AbMPEG1 in hemocytes and gills.
- Recombinant AbMPEG1 exhibited antibacterial activity against Gram-negative and Gram-positive bacteria.
Conclusions:
- AbMPEG1 plays a significant role in the innate immune defense of disk abalone.
- AbMPEG1 initiates immune responses upon pathogen invasion, contributing to host protection.
- The findings highlight AbMPEG1 as a potential target for aquaculture health management.
