Enzyme-cargo encapsulation peptides bind between tessellating tiles of the bacterial microcompartment shell

Area of Science:

• Biochemistry
• Cell Biology
• Structural Biology

Background:

• Bacterial microcompartments (BMCs) are protein-bound organelles found in prokaryotes.
• They compartmentalize metabolic pathways, enhancing efficiency and protecting the cell.
• Enzymes within BMCs often have encapsulation peptides, but their binding site was unknown.

Purpose of the Study:

• To identify the binding site of cargo-encapsulation peptides on BMC shell proteins.
• To elucidate the mechanism of enzyme targeting and its role in BMC assembly.

Main Methods:

• In silico docking studies were performed to model peptide-shell protein interactions.
• Structural analysis of the hydrophobic groove between shell protein subunits.

Main Results:

• Encapsulation peptides bind to a hydrophobic groove formed by tessellating shell protein subunits.
• This binding model explains previous experimental difficulties and supports the orientation of shell proteins.
• Peptide binding promotes shell assembly and influences BMC size and shape.

Conclusions:

• The hydrophobic groove is the primary binding site for encapsulation peptides.
• Understanding this interaction is crucial for engineering BMCs and developing disease prevention strategies targeting encapsulation.