Two goose-type lysozymes in Mytilus galloprovincialis: possible function diversification and adaptive evolution

Area of Science:

• Marine Biology
• Immunology
• Evolutionary Biology

Background:

• Lysozymes are crucial antimicrobial enzymes found in various organisms.
• Mussels possess immune systems that rely on enzymes like lysozymes to combat pathogens.
• Understanding mussel lysozymes can provide insights into invertebrate immunity and digestive processes.

Purpose of the Study:

• To identify and characterize two goose-type lysozymes (MGgLYZ1 and MGgLYZ2) from the mussel Mytilus galloprovincialis.
• To investigate the expression patterns, antibacterial activity, and evolutionary aspects of these lysozymes.
• To elucidate the distinct functional roles of MGgLYZ1 and MGgLYZ2 in the mussel.

Main Methods:

• Gene identification and mRNA expression analysis (including response to bacterial challenge).
• Recombinant protein expression and antibacterial activity assays (Minimum Inhibitory Concentration).
• Bioinformatic analysis of protein sequences, genomic structure, and selection pressures.

Main Results:

• MGgLYZ1 and MGgLYZ2 exhibit broad-spectrum antibacterial activity, particularly against Pseudomonas putida.
• MGgLYZ1 is widely expressed and responds to bacterial challenge, suggesting an immune role.
• MGgLYZ2 is predominantly expressed in the hepatopancreas, functions optimally at acidic pH, and shows signs of positive selection, indicating a digestive role.

Conclusions:

• MGgLYZ1 plays a significant role in the mussel's innate immune response.
• MGgLYZ2 is likely a digestive lysozyme adapted to acidic environments and has evolved under positive selection.
• The conserved genomic structure suggests gene duplication as the origin of these two lysozymes.