Crystal Structures of Trimethoprim-Resistant DfrA1 Rationalize Potent Inhibition by Propargyl-Linked Antifolates.
Multidrug-resistant Enterobacteriaceae, notably Escherichia coli and Klebsiella pneumoniae, have become major health concerns worldwide. Resistance to effective therapeutics is often carried by class I and II integrons that can confer insensitivity to carbapenems, extended spectrum β-lactamases, the antifolate trimethoprim, fluoroquinolones, and aminoglycosides. Specifically of interest to the study here, a prevalent gene (dfrA1) coding for an insensitive dihydrofolate reductase (DHFR) confers 190- or 1000-fold resistance to trimethoprim for K. pneumoniae and E. coli, respectively. Attaining inhibition of both the wild-type and resistant forms of the enzyme is critical for new antifolates. For several years, we have been developing the propargyl-linked antifolates (PLAs) as effective inhibitors against trimethoprim-resistant DHFR enzymes. Here, we show that the PLAs are active against both the wild-type and DfrA1 DHFR proteins. We report two high-resolution crystal structures of DfrA1 bound to potent PLAs. The structure-activity relationships and crystal structures will be critical in driving the design of broadly active inhibitors against wild-type and resistant DHFR.
Department of Pharmaceutical Sciences, University of Connecticut , 69 North Eagleville Road, Storrs, Connecticut 06269, United States.
Michael N
MN
Lombardo
Department of Pharmaceutical Sciences, University of Connecticut , 69 North Eagleville Road, Storrs, Connecticut 06269, United States.
Narendran
N
G-Dayanandan
Department of Pharmaceutical Sciences, University of Connecticut , 69 North Eagleville Road, Storrs, Connecticut 06269, United States.
Dennis L
DL
Wright
Department of Pharmaceutical Sciences, University of Connecticut , 69 North Eagleville Road, Storrs, Connecticut 06269, United States.
Amy C
AC
Anderson
D000900:Anti-Bacterial Agents / Q000737:chemistry* / Q000494:pharmacology*; D001426:Bacterial Proteins / Q000737:chemistry; D018360:Crystallography, X-Ray; D004926:Escherichia coli / Q000201:enzymology; D005493:Folic Acid Antagonists / Q000737:chemistry* / Q000494:pharmacology*; D006801:Humans; D032023:Integrons; D007711:Klebsiella pneumoniae / Q000201:enzymology; D013329:Structure-Activity Relationship; D013762:Tetrahydrofolate Dehydrogenase / Q000737:chemistry*; D014295:Trimethoprim / Q000494:pharmacology*; D014296:Trimethoprim Resistance / Q000187:drug effects*; D001618:beta-Lactamases / Q000378:metabolism
D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; D005493:Folic Acid Antagonists; D014295:Trimethoprim; D013762:Tetrahydrofolate Dehydrogenase; D001618:beta-Lactamases
DfrA1; Enterobacteriaceae; antifolate; resistance; trimethoprim