Fig. 2: 4′-DTMP has enhanced and selective antimicrobial activity against E. coli with the L28R mutation in DHFR.
From: A trimethoprim derivative impedes antibiotic resistance evolution
a Structure of Trimethoprim (TMP) and 4′-desmethyltrimethoprim (4′-DTMP). b Representative drug dose response curves for TMP (gray) and 4′-DTMP (teal) against E. coli harboring wildtype DHFR (wild-type, left) or DHFR with the L28R mutation (right). All DHFR mutant strains were constructed in MG1655 attTn7::pRNA1-tdCherry (NDL47, see Methods” section) by replacing the chromosomal folA gene with the corresponding chemically synthesized folA variant sandwiched between kanamycin and chloramphenicol resistance genes. c Activity of 4′-DTMP (teal) is indistinguishable from TMP (gray) activity against wildtype E. coli (n = 7 replicates), whereas 4’-DTMP (teal) has ~30-fold higher antimicrobial activity (p = 9.597 × 10−4, n = 14 replicates) compared to TMP (gray) against E. coli with L28R- mutation. d Activity of 4′-DTMP (teal) against wild-type and other frequently-observed E. coli mutants with single DHFR mutations is indistinguishable from TMP activity (gray) (n = 7 replicates), except L28R (p = 3.5912 × 10−6). e Indistinguishable antimicrobial activities of TMP (gray) and 4′-DTMP (teal) against other Gram-negative and Gram-positive bacteria as well as a clinical E. coli isolate (n = 3 replicates). Student’s t-test (two tailed) is used to quantify significance of IC95 value differences in all panels (*p < 0.05, **p < 0.01, and ***p < 0.001, error bars show the standard deviation, center of the error bars corresponds to the mean value of the measurements.).
