Antigen 43-mediated autotransporter display, a versatile bacterial cell surface presentation system.

Area of Science:

• Microbiology
• Molecular Biology
• Biotechnology

Background:

• Antigen 43 (Ag43) is a self-recognizing outer membrane protein from Escherichia coli.
• Ag43 functions as an autotransporter, containing all necessary information for its own transport and secretion.
• Its structure comprises alpha and beta subunits, with the beta-subunit forming an outer membrane translocator.

Purpose of the Study:

• To evaluate Ag43 as a scaffold for surface display of foreign protein segments.
• To demonstrate the capacity of the Ag43 alpha-module to display folded protein inserts and functional domains.
• To explore the utility of Ag43 in diverse Gram-negative bacterial hosts.

Main Methods:

• Engineering Ag43 chimeras by inserting foreign protein segments into the Ag43 alpha-module.
• Assessing the surface display and correct folding of inserted proteins, including the FimH lectin domain.
• Testing the display capability in different Gram-negative bacteria, including an attenuated Salmonella strain.

Main Results:

• The Ag43 alpha-module successfully accommodated and displayed correctly folded protein inserts.
• Functional protein domains, such as the FimH lectin domain, were effectively presented on the bacterial surface.
• Heterologous cysteine bridges did not impede surface display, and Ag43 chimeras were correctly processed.
• The Ag43 system demonstrated versatility by enabling display in multiple Gram-negative bacteria, including Salmonella.

Conclusions:

• The Ag43 system is a simple yet powerful tool for the surface display of foreign proteins and functional domains.
• Ag43 chimeras are stable, correctly processed, and can be released optionally.
• The ability to display Ag43 in various Gram-negative bacteria expands its application potential in biotechnology and research.