Bacterial Protease Mechanisms in Host Interaction

Bacterial proteases are critical virulence factors that mediate host colonisation, immune evasion and tissue invasion. These enzymes cleave host proteins ranging from structural components of the extracellular matrix to cell–cell adhesion molecules and signalling receptors. Pathogens deploy a diverse arsenal of serine, cysteine and metalloproteases via specialised secretion routes, including autotransporters, type VI secretion systems and outer membrane vesicles. Proteolytic modification of host substrates such as actin and E-cadherin drives cytoskeletal remodelling, disrupts barrier integrity and triggers host signalling cascades that facilitate bacterial entry. Fine tuning of protease activity and specificity is often achieved through propeptide domains or local co-factors, ensuring temporal and spatial control during infection. Understanding these molecular mechanisms underpins efforts to design inhibitors that block protease-driven invasion and to harness bacterial proteases as tools for biomedical research.

Research from Nature Portfolio

Recent structural studies of a subtilisin-like autotransporter passenger domain have revealed a unique β-helix scaffold bearing finger-like loops around the catalytic site, which mediates epithelial cell entry and cytotoxicity. This work illuminates how autotransporter proteases diversify substrate recognition and deliver enzymatic activity across the outer membrane. In parallel, the development of an internally quenched fluorescent peptide substrate for protealysin has established a robust quantitative assay, defining kinetic parameters and demonstrating high specificity within the M4 peptidase family. This tool now enables precise measurements of protealysin activity and comparative studies of related metalloproteases.

Bacterial Protease Mechanisms in Host Interaction publication trend

The graph below shows the total number of articles in bacterial protease mechanisms in host interaction across all publications each year (not limited to Nature Index journals).

Technical terms

Autotransporter: A two-domain secretion protein that translocates its own passenger (often a protease) across the outer membrane.

Metalloprotease: A protease requiring a metal ion, typically zinc, for catalytic activity and substrate binding.

Type VI secretion system: A phage-like apparatus that injects effector proteins, including proteases, directly into target cells.

Outer membrane vesicles: Nano-sized blebs shed from Gram-negative bacteria carrying enzymes and virulence factors to distant host sites.

E-cadherin: A calcium-dependent adhesion molecule on epithelial cells that, when cleaved, alters cell–cell contacts and signalling.

Actin polymerisation: The assembly of globular actin monomers into filamentous structures vital for cell shape and motility.

References

1. Crystal structure of a subtilisin-like autotransporter passenger domain reveals insights into its cytotoxic function. Nature Communications (2023).
2. Host-Cell-Dependent Roles of E-Cadherin in Serratia Invasion. International Journal of Molecular Sciences (2023).
3. Bacterial Actin-Specific Endoproteases Grimelysin and Protealysin as Virulence Factors Contributing to the Invasive Activities of Serratia. International Journal of Molecular Sciences (2020).
4. The Balance between Protealysin and Its Substrate, the Outer Membrane Protein OmpX, Regulates Serratia proteamaculans Invasion. International Journal of Molecular Sciences (2024).
5. An Internally Quenched Fluorescent Peptide Substrate for Protealysin. Scientific Reports (2019).
6. How bacterial pathogens colonize their hosts and invade deeper tissues. Microbes and Infection (2015).