Abstract:
Phosphorodiamidate morpholino oligomers (PMOs) are novel antisense drugs in the early stages
of development. These synthetic DNA mimics contain the same bases found in DNA and anneal
to RNA in a complementary fashion. PMOs have been designed that target genes responsible for
producing essential proteins in organisms such as Escherichia coli. After the PMOs get into the
bacterial cell (with peptides attached to facilitate their entry), they block translation of the
targeted gene by annealing to mRNA and kill the cell. In this way, PMOs can be used as
antibiotics.
Tests with varying concentrations of drugs were completed both in vitro and in vivo (with mice)
showing that PMOs can be as effective as ampicillin in stopping a bacterial infection of E. coli.
This thesis will cover some of these tests, as well as experiments in which PMO-resistant mutant
strains were discovered and isolated. Further work with several peptide-PMO conjugates showed
that resistance was not a result of a change in the PMO target sequence and appeared to be
peptide-related. Finally, out of two experiments designed to pinpoint genes required for E. coli to
be susceptible to peptide-PMOs, a transposon knock-out experiment was successful in generating
a PMO-resistant mutant and singling out nmpC as a gene of interest. Though this gene is
identified as a pseudogene on the BLAST website, this research suggests that nmpC could have a
function. Future research with this gene as well as repeating this method to find other genes of
interest may increase knowledge of how PMOs work and aid in the design of more effective
PMOs.
