Investigation into the molecular basis for serotype differences in Pseudomonas aeruginosa serogroup 05



Newton, Gregory James

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University of Guelph


The goal of this thesis was to identify the molecular basis for some of the structural differences observed in the B-band LPS O antigen of serogroup O5 using bacteriophage D3, a lysogenic phage of 'P. aeruginosa ' PAO1 (serotype O5). Bacteriophage D3 is capable of lysogenizing ' P. aeruginosa' PAO1, converting the O antigen from O5 to O16 and ' O'-acetylating the 'N'-acetylfucosamine moiety. To investigate the pathway of lysogenic conversion, a fragment from the D3 genome capable of mediating serotypic conversion identical to the D3 lysogen strain (AK1380) was isolated. The PAO1 transformants containing this 3.6-kb fragment of D3 DNA in a plasmid exhibited identical LPS banding patterns to serotype O16 in silver-stained SDS-PAGE gels, and displayed reactivity to an antibody specific for 'O'-acetyl groups. Using the computer prediction software, MEME, Oac was found to have five highly conserved amino acid motifs that are shared with homologous exopolysaccharide acetylases indicating potential functional domains. (Abstract shortened by UMI.)



Pseudomonas aeruginosa, Serogroup O5, molecular basis, serotype differences, lysogenic conversion