Cryo-EM structure of Mycobacterium smegmatis DyP-loaded encapsulin

Area of Science:

• Structural biology
• Microbiology
• Biochemistry

Background:

• Encapsulins are protein shells found in prokaryotes, often housing enzymes like peroxidases.
• Dye-decolorizing peroxidase (DyP)-type peroxidases protect cells from oxidative stress.
• The interaction and function of encapsulins with their cargo are not well understood.

Purpose of the Study:

• To determine the high-resolution structure of a native encapsulin-DyP complex from Mycobacterium smegmatis.
• To elucidate the interaction between the encapsulin shell and its DyP cargo.
• To propose a mechanism for hydrogen peroxide removal and explore therapeutic potential.

Main Methods:

• Isolation of a native encapsulin-DyP complex from Mycobacterium smegmatis.
• High-resolution structure determination using cryogenic electron microscopy (cryo-EM).
• Structural analysis to understand protein-protein interactions and functional mechanisms.

Main Results:

• The encapsulin forms an icosahedral shell enclosing a dodecameric DyP cargo.
• The DyP cargo, composed of two hexamers, spans the interior of the encapsulin.
• The encapsulin shell stabilizes the dodecameric DyP structure.
• A potential mechanism for hydrogen peroxide detoxification was proposed based on structural features.

Conclusions:

• The DyP is the primary cargo of mycobacterial encapsulins.
• The encapsulin shell plays a crucial role in stabilizing the DyP cargo.
• The structure provides insights into oxidative stress protection mechanisms.
• Mycobacterial encapsulins and their DyP cargo represent potential targets for antituberculosis drug discovery.