Plasmid mediated complementation of wza in Escherichia coli K30 strain CWG281 restores erythromycin sensitivity

SUMMARY In Escherichia coli serotype K30, the outer membrane channel protein Wza, involved in capsule secretion, has been genetically linked to macrolide sensitivity. Deletion of wza in erythromycin-sensitive E. coli K30 confers resistance to erythromycin. In this study, we tested whether complementation of wza would restore sensitivity to erythromycin in the wza knockout mutant E. coli CWG281. wza was cloned into the arabinose-inducible pBAD24 expression vector using Gibson assembly and then transformed into E. coli CWG281. Induction of pBAD24-wzaK30 with 0.008% arabinose was observed to restore erythromycin sensitivity using Kirby-Bauer disk diffusion assays. Interestingly, induction of pBAD24-wzaK30 with 1% arabinose was found to impair growth of E. coli CWG281 transformants. From this study, we conclude that complementation of wza in E. coli CWG281 is sufficient to restore erythromycin sensitivity. We further conclude that overexpression of wza in E. coli CWG281 impairs cell growth.