Investigating the mechanisms of secretion of the moonlighting proteins Enolase and Fructose-1, 6-Bisphosphate Aldolase in Neisseria meningitidis

Atwah, Banan (2019) Investigating the mechanisms of secretion of the moonlighting proteins Enolase and Fructose-1, 6-Bisphosphate Aldolase in Neisseria meningitidis. PhD thesis, University of Nottingham.

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Abstract

Neisseria meningitidis is an obligate commensal of humans that mainly colonises the nasopharynx. It is also an important cause of serious diseases, such as meningitis and sepsis. N. meningitidis uses several secretion systems (type I, type Va, type Vb, and type Vc) for secreting proteins, which enable the bacteria to modulate their cell surface and evade the human immune system.

The moonlighting proteins fructose bis-1, 6-phosphate aldolase (FBA) and enolase were previously shown to localise to the surface of N. meningitidis. The mechanisms of secretion of both proteins were investigated in this study. Specifically, lysine residue 337 of enolase was substituted to investigate its role in secretion since in Escherichia coli mutation of the corresponding residue has been reported to decrease export efficiency.

This study proposes that K337E substitution in meningococcal enolase causes a growth defect confirming an important functional role of this residue. However, its role in the localisation of the protein to the meningococcal cell surface is still not confirmed despite the several attempts to enhance enolase expression.

The alanine residue 14 in the predicted cleavage site of the N-terminal region of FBA was substituted to investigate the role of the putative signal peptide in the surface localisation. Immunoblot analysis showed a reduction in FBA expression compared to the MC58ΔcbbA cbbAEct. Sub-cellular fractionation suggested that this mutation affected protein expression rather than its localisation to the meningococcal cell surface.

Item Type: Thesis (University of Nottingham only) (PhD)
Supervisors: Turner, David
Oldfield, Neil
Wooldridge, Karl
Keywords: Neisseria meningitides; Moonlighting proteins; Secretion
Subjects: Q Science > QR Microbiology
Faculties/Schools: UK Campuses > Faculty of Medicine and Health Sciences > School of Life Sciences
Item ID: 56419
Depositing User: Atwah, Banan
Date Deposited: 08 Aug 2019 10:19
Last Modified: 07 May 2020 10:47
URI: http://eprints.nottingham.ac.uk/id/eprint/56419

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