Dimeric Structure of the Bacterial Extracellular Foldase PrsA

Area of Science:

• Microbiology
• Structural Biology
• Biochemistry

Background:

• Protein secretion into the cell wall space is vital for Gram-positive bacteria.
• Extracellular foldase PrsA facilitates folding and maturation of secreted proteins.
• PrsA is a lipid-anchored protein located on the cell membrane's outer leaflet.

Purpose of the Study:

• To elucidate the structural characteristics and functional mechanisms of the Bacillus subtilis PrsA protein.
• To investigate the structural similarities and differences between PrsA and other bacterial chaperones.
• To understand the role of PrsA's unique dimerization in substrate interaction and protection.

Main Methods:

• X-ray crystallography was used to determine the crystal structure of Bacillus subtilis PrsA.
• Nuclear Magnetic Resonance (NMR) experiments were performed to study protein-protein interactions.
• Structural comparisons were made with known bacterial chaperones like trigger factor and SurA.

Main Results:

• The crystal structure of PrsA revealed a parvulin-type prolyl isomerase domain within a composite NC domain.
• PrsA shares domain architecture similarities with trigger factor and SurA, despite lacking sequence homology.
• PrsA exhibits a unique dimerization mode via its NC domain, forming a crevice potentially for substrate protection.
• NMR data confirmed dynamic interactions between PrsA's domains and secretion propeptides.

Conclusions:

• PrsA possesses a unique structural organization and dimerization capability essential for its function.
• The identified structural features and interactions suggest a role for PrsA in preventing substrate aggregation during secretion.
• PrsA's interaction with propeptides highlights its importance in targeting and processing secreted proteins in Gram-positive bacteria.