5ECX image
Entry Detail
PDB ID:
5ECX
Title:
Klebsiella pneumoniae DfrA1 complexed with NADPH and 6-ethyl-5-(3-(6-(pyridin-4-yl)benzo[d][1,3]dioxol-4-yl)but-1-yn-1-yl)pyrimidine-2,4-diamine
Biological Source:
Source Organism:
Host Organism:
PDB Version:
Deposition Date:
2015-10-20
Release Date:
2016-05-18
Method Details:
Experimental Method:
Resolution:
1.95 Å
R-Value Free:
0.26
R-Value Work:
0.21
R-Value Observed:
0.21
Space Group:
P 31 2 1
Macromolecular Entities
Polymer Type:polypeptide(L)
Description:Dehydrofolate reductase type I
Chain IDs:A, B
Chain Length:157
Number of Molecules:2
Biological Source:Klebsiella pneumoniae
Primary Citation
Crystal Structures of Trimethoprim-Resistant DfrA1 Rationalize Potent Inhibition by Propargyl-Linked Antifolates.
ACS Infect Dis 2 149 156 (2016)
PMID: 27624966 DOI: 10.1021/acsinfecdis.5b00129

Abstact

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.

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