The Porphyromonas gingivalis lipid A 1-phosphatase LpxE requires a functional type IX secretion system for its activity

Journal article

Background: Porphyromonas gingivalis is a Gram-negative bacterium that plays a central role in the development of periodontal disease. It uses a type IX secretion system (T9SS) to export virulence factors to the bacterial surface where they are attached to A-LPS, one of the two forms of lipopolysaccharide (LPS) produced in P. gingivalis, and then packaged into outer membrane vesicles (OMVs). We previously showed that 1-P dephosphorylation of the lipid A component of LPS is regulated by the T9SS outer membrane protein PorV, and this is linked to membrane destabilisation and OMV blebbing/formation. Objective: This study aimed to investigate whether other T9SS outer membrane proteins are required for correct OMV biogenesis. Design: We examined gingipain activity, gingipain secretion, A-LPS production, OMV morphology, and lipid A structure in P. gingivalis W50, T9SS mutant strains, and a lipid A 1-phosphatase (ΔlpxE) mutant strain. Results: A functional T9SS is required for LpxE activity and correct vesicle formation, and this is likely through the function of an exported type IX-cargo protein. Conclusion: This study provides insight into a new mechanism that links type IX cargo sorting with OMV blebbing, which may also be present in other Bacteroidota that colonise the gut and oral cavity.

Authors: Wang, S; Liu, Y; Zhang, B; Aduse-Opoku, J; Buccafusca, R

• Publication status: Published
• Peer review status: Peer reviewed
• Publisher: Taylor and Francis Group
• Journal: Journal of Oral Microbiology
• Volume: 17
• Issue: 1
• Pages: 2600179
• Article number: 2600179
• Publication date: 2025-12-31
• Acceptance date: 2025-12-02
• DOI: 10.1080/20002297.2025.2600179
• EISSN: 2000-2297
• ISSN: 2000-2297
• Language: English
• Keywords: lipid A; Porphyromonas gingivalis; type IX secretion system; outer membrane vesicle; lipopolysaccharide