Dissecting protein-protein interactions facilitating secretion of the virulence factor EspC by enteropathogenic Escherichia coli
Bishop, Keith (2009) Dissecting protein-protein interactions facilitating secretion of the virulence factor EspC by enteropathogenic Escherichia coli. MPhil thesis, University of Nottingham.
This study investigates the domain structure and secretion of the autotransporter (AT) EspC, secreted by enteropathogenic Escherichia coli (EPEC). The boundaries of the archetypical signal peptide and beta-domain surrounding the passenger domain of EspC were established. Then, structural modelling was used to define a region of EspC between the passenger- and β-domains, termed the inter-domain, which may comprise a passenger- chaperone domain. Yeast two-hybrid and co-purification approaches were subsequently used to assess protein-protein interactions between individual EspC domains and with a putative secretion accessory factor, YbgC. Direct interaction between the EspC passenger- and inter-domain was observed, consistent with a proposed chaperone function for the inter-domain. Structural modelling identified conserved surface motifs within the inter-region as targets for mutagenesis to determine their influence upon EspC secretion. Complementation of an EPEC espC mutant strain with inter-domain EspC mutants showed profound affects on secretion. Furthermore, these mutants had a dominant-negative affect on wildtype EspC secretion, affecting bacterial cell viability.
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