The role of glyceraldehyde 3-phosphate dehydrogenase (GapA-1) in Neisseria meningitidis adherence to human cells

Tunio, Sarfraz A.; Oldfield, Neil J.; Ala'Aldeen, Dlawer A A; Wooldridge, Karl G.; Turner, David P J

Abstract

Background
Glyceraldehyde 3-phosphate dehydrogenases (GAPDHs) are cytoplasmic glycolytic enzymes, which although lacking identifiable secretion signals, have also been found localized to the surface of several bacteria (and some eukaryotic organisms); where in some cases they have been shown to contribute to the colonization and invasion of host tissues. Neisseria meningitidis is an obligate human nasopharyngeal commensal which can cause life-threatening infections including septicaemia and meningitis. N. meningitidis has two genes, gapA-1 and gapA-2, encoding GAPDH enzymes. GapA-1 has previously been shown to be up-regulated on bacterial contact with host epithelial cells and is accessible to antibodies on the surface of capsule-permeabilized meningococcal cells. The aims of this study were: 1) to determine whether GapA-1 was expressed across different strains of N. meningitidis; 2) to determine whether GapA-1 surface accessibility to antibodies was dependant on the presence of capsule; 3) to determine whether GapA-1 can influence the interaction of meningococci and host cells, particularly in the key stages of adhesion and invasion.

Results
In this study, expression of GapA-1 was shown to be well conserved across diverse isolates of Neisseria species. Flow cytometry confirmed that GapA-1 could be detected on the cell surface, but only in a siaD-knockout (capsule-deficient) background, suggesting that GapA-1 is inaccessible to antibody in in vitro-grown encapsulated meningococci. The role of GapA-1 in meningococcal pathogenesis was addressed by mutational analysis and functional complementation. Loss of GapA-1 did not affect the growth of the bacterium in vitro. However, a GapA-1 deficient mutant showed a significant reduction in adhesion to human epithelial and endothelial cells compared to the wild-type and complemented mutant. A similar reduction in adhesion levels was also apparent between a siaD-deficient meningococcal strain and an isogenic siaD gapA-1 double mutant.

Conclusions
Our data demonstrates that meningococcal GapA-1 is a constitutively-expressed, highly-conserved surface-exposed protein which is antibody-accessible only in the absence of capsule. Mutation of GapA-1 does not affect the in vitro growth rate of N. meningitidis, but significantly affects the ability of the organism to adhere to human epithelial and endothelial cells in a capsule-independent process suggesting a role in the pathogenesis of meningococcal infection.

Citation

Tunio, S. A., Oldfield, N. J., Ala'Aldeen, D. A. A., Wooldridge, K. G., & Turner, D. P. J. (2010). The role of glyceraldehyde 3-phosphate dehydrogenase (GapA-1) in Neisseria meningitidis adherence to human cells. BMC Microbiology, 10, Article 280. https://doi.org/10.1186/1471-2180-10-280

• Journal Article Type: Article
• Acceptance Date: Nov 9, 2010
• Online Publication Date: Nov 9, 2010
• Publication Date: Nov 11, 2010
• Deposit Date: Aug 2, 2022
• Publicly Available Date: Aug 5, 2022
• Journal: BMC Microbiology
• Electronic ISSN: 1471-2180
• Publisher: Springer Verlag
• Peer Reviewed: Peer Reviewed
• Volume: 10
• Article Number: 280
• DOI: https://doi.org/10.1186/1471-2180-10-280
• Public URL: https://nottingham-repository.worktribe.com/output/3129860
• Publisher URL: https://bmcmicrobiol.biomedcentral.com/articles/10.1186/1471-2180-10-280