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Abstract
Outer membrane protein A plays an essential role in horizontal gene transfer in Escherichia coli by acting as a docking protein for the pilus during conjugation. The purpose of this study was to assess the ability of plasmidencoded and L-arabinose induced OmpA expression in a pBAD expression vector to restore mutant ompA phenotype back to wild type. The Escherichia coli recipient strains used were ompA wild-type strain BW25113, ompAdeletion mutants LVYY11w-1 with empty pBAD TOPO plasmid, LVYY11w-2 with pBAD TOPO inserted with ompA, and JW0940 without plasmid transformation. The F’ donor used to test conjugation was Escherichia coli strain JCFLOxK1200. Relative conjugation efficiencies of mutant recipient strains were compared to the wildtype strain and with each other through statistical analysis. Our results showed that the wild-type BW25113 strain had the highest relative conjugation efficiency. All other ompAdeletion mutant recipients had reduced relative conjugation efficiencies when L-arabinose levels varied between 0% and 2% (w/v). Because there was no statistically significant difference in conjugation efficiency among strains LVYY11w-2, LVYY11w-1, and JW0940, we concluded that the plasmid-encoded OmpA might be misfolded, or falsely processed. Furthermore, since the ompA gene inserted in the plasmid was from Escherichia coli strain MG1655, its encoded protein might play different roles compared to OmpA protein in wild-type strain BW25113.