Cloning, expression and functional analysis of FctX: a putative pilus associated adhesin of Group A Streptococcus

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dc.contributor.advisor Proft, T en
dc.contributor.advisor Baker, T en
dc.contributor.advisor Young, P en
dc.contributor.author Govind, Bhavesh en
dc.date.accessioned 2011-08-15T20:04:23Z en
dc.date.issued 2011 en
dc.identifier.uri http://hdl.handle.net/2292/7332 en
dc.description Full text is available to authenticated members of The University of Auckland only. en
dc.description.abstract The gram-positive bacterium Streptococcus pyogenes also known as Group A Streptococcus (GAS) is a human pathogen which causes a range of superficial diseases infecting the skin and upper-respiratory tract. On rare occasions, GAS causes more severe diseases such as necrotizing fasciitis and Streptococcal toxic shock syndrome as well as post infection sequelae. The ability of GAS to cause such a wide range of diseases is attributed to its repertoire of virulence factors. A surface associated virulence factor involved in host cell attachment, colonization and biofilm production is the GAS pilus. Pili are long hair-like fibres which radiate from the bacterial cell surface and have only recently been discovered in gram-positive pathogens such as GAS. Early studies have revealed that the GAS pilus consists of a major pilin protein which forms the backbone structure and one or two minor pilin proteins which are associated to the pilus and required for its function. The genes which encode the pilin subunits as well as sortase enzymes which are required for pilus assembly are all found within a discrete region of the GAS genome known as the fibronectin/collagen-binding T-antigen (FCT) region. Genome analysis of a number of GAS strains has identified nine different FCT regions (FCT-1 to FCT-9), each carrying a unique pilus operon. The FCT-1 region found in serotype M6 strains of GAS contains the major pilin, tee6, one minor pilin fctX and the pilus assembly sortase, srtB. The aim of this project was to study the function of fctX, thought to encode a putative pilus associated adhesin. In this study, a non-pathogenic relative of GAS, Lactococcus lactis was used as a model organism into which the fctX gene was cloned and expressed in, creating L. lactis gainof- function mutants. After verifying the surface expression of FctX, the mutants were used to infect host cell lines of GAS. Results from adherence assays show that the mutants had an enhanced ability to adhere to both HaCat (keratinocyte) and Detroit- 562 (pharynx) cell lines which represent the two main colonisation sites of GAS. Insights gained from this research will aid in the functional characterisation of fctX, leading to a better understanding of how GAS uses its pilus as a virulence factor. As our knowledge in this field expands, new opportunities of using the pilus as a vaccine target to immunise against GAS infections arise. en
dc.relation.ispartof Masters Thesis - University of Auckland en
dc.rights Restricted Item. Available to authenticated members of The University of Auckland. en
dc.rights Items in ResearchSpace are protected by copyright, with all rights reserved, unless otherwise indicated. en
dc.rights.uri https://researchspace.auckland.ac.nz/docs/uoa-docs/rights.htm en
dc.rights.uri http://creativecommons.org/licenses/by-nc-sa/3.0/nz/ en
dc.title Cloning, expression and functional analysis of FctX: a putative pilus associated adhesin of Group A Streptococcus en
dc.type Thesis en
thesis.degree.grantor The University of Auckland en
thesis.degree.level Masters en
dc.rights.holder Copyright: The author en
pubs.elements-id 218793 en
pubs.record-created-at-source-date 2011-08-16 en


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