Dihydrofolate Reductase: X-ray Structure of the Binary Complex with Methotrexate

Abstract

A central eight-stranded beta-pleated sheet is the main feature of the polypeptide backbone folding in dihydrofolate reductase. The innermost four strands and two bridging helices are geometrically similar to but are connected in a different way from those in the dinucleotide binding domains found in nicotinamide-adenine dinucleotide-linked dehydrogenases. Methotrexate is bound in a 15-angstrom-deep cavity with the pteridine ring buried in a primarily hydrophobic pocket, although a strong interaction occurs between the side chain of aspartic acid 27 and N(1), N(8), and the 2-amino group of methotrexate.

The charge state of trimethoprim bound to Lactobacillus casei dihydrofolate reductase

“…The recent determination of the crystal structure of the enzyme-trimethoprim complex [15] shows that the orientation of the 2,4-diaminopyrimidine ring in the binding site is very similar to that of the analogous part of methotrexate [11,16]. We now report ~3C NMR experiments which confirm this similarity in the binding of the two inhibitors in solution, and show that trimethoprim is also protonated when bound.…”

Massive overproduction of dihydrofolate reductase in bacteria as a response to the use of trimethoprim

“…The ribosome-binding site compared to that of E. coli K 12 showed seven base changes, two of which resulted in a five-base sequence of complementarity with the 3'-end of ribosomal 16s RNA. The structural gene of the enzyme was identical to that of E. coli K12, with nine exceptions, one of whch resulted in the substitution of Gly for Trp at amino acid position 30, which is known to be located at the substrate-binding site [4].…”

Allosteric Communication in Dihydrofolate Reductase: Signaling Network and Pathways for Closed to Occluded Transition and Back

“…High resolution crystal structures show that the E. Coli DHFR enzyme has eight β-strands and four α-helices interspersed with flexible loops that connect the secondary structural elements [29,30]. The structure of DHFR can be partitioned into adenosine binding and loop subdomains [30].…”

“…In addition, the conformational changes in E.coli DHFR in response to binding have been inferred using various experimental techniques, including X-ray crystallography, fluorescence, nuclear magnetic resonance (NMR) [21,29,30]. Comparison of the CS and OS structures shows that the conformations of Met20 loop undergoes the largest change during the reaction cycle.…”