PDBsum entry 6prb

Oxidoreductase/inhibitor

PDB id: 6prb

Contents

Protein chain

162 a.a.

Ligands

R0Y-OWM

GOL

NAP

Waters ×128

PDB id:

6prb

Name:

Oxidoreductase/inhibitor

Title:

S. Aureus dihydrofolate reductase co-crystallized with cyclopropyl- dimethyoxydihydropthalazine inhibitor and NADP(h)

Structure:

Dihydrofolate reductase. Chain: a. Synonym: dhfr. Engineered: yes

Source:

Staphylococcus aureus. Organism_taxid: 1280. Gene: fola. Expressed in: escherichia coli. Expression_system_taxid: 562

Resolution:

2.00Å R-factor: 0.192 R-free: 0.238

Authors:

C.R.Bourne,L.M.Thomas

Key ref:

N.P.Muddala et al. (2020). Inhibitor design to target a unique feature in the folate pocket of Staphylococcus aureus dihydrofolate reductase. Eur J Med Chem, 200, 112412. PubMed id: 32502861 DOI: 10.1016/j.ejmech.2020.112412

Date:

10-Jul-19 Release date: 17-Jun-20

Protein chain

P0A017  (DYR_STAAU) -  Dihydrofolate reductase from Staphylococcus aureus

Seq: 159 a.a.

Struc: 162 a.a.

Enzyme reactions

• Enzyme class: E.C.1.5.1.3 - dihydrofolate reductase.
• Pathway: Folate Coenzymes
• Reaction: (6S)-5,6,7,8-tetrahydrofolate + NADP⁺ = 7,8-dihydrofolate + NADPH + H⁺

(6S)-5,6,7,8-tetrahydrofolate + NADP(+) (Bound ligand (Het Group name = NAP) corresponds exactly) = 7,8-dihydrofolate + NADPH + H(+)

Molecule diagrams generated from .mol files obtained from the KEGG ftp site

reference

DOI no: 10.1016/j.ejmech.2020.112412

Eur J Med Chem 200:112412 (2020)

PubMed id: 32502861

Inhibitor design to target a unique feature in the folate pocket of Staphylococcus aureus dihydrofolate reductase.

N.P.Muddala, J.C.White, B.Nammalwar, I.Pratt, L.M.Thomas, R.A.Bunce, K.D.Berlin, C.R.Bourne.

ABSTRACT

Staphylococcus aureus (Sa) is a serious concern due to increasing resistance to antibiotics. The bacterial dihydrofolate reductase enzyme is effectively inhibited by trimethoprim, a compound with antibacterial activity. Previously, we reported a trimethoprim derivative containing an acryloyl linker and a dihydophthalazine moiety demonstrating increased potency against S. aureus. We have expanded this series and assessed in vitro enzyme inhibition (K_i) and whole cell growth inhibition properties (MIC). Modifications were focused at a chiral carbon within the phthalazine heterocycle, as well as simultaneous modification at positions on the dihydrophthalazine. MIC values increased from 0.0626-0.5 μg/mL into the 0.5-1 μg/mL range when the edge positions were modified with either methyl or methoxy groups. Changes at the chiral carbon affected K_i measurements but with little impact on MIC values. Our structural data revealed accommodation of predominantly the S-enantiomer of the inhibitors within the folate-binding pocket. Longer modifications at the chiral carbon, such as p-methylbenzyl, protrude from the pocket into solvent and result in poorer K_i values, as do modifications with greater torsional freedom, such as 1-ethylpropyl. The most efficacious K_i was 0.7 ± 0.3 nM, obtained with a cyclopropyl derivative containing dimethoxy modifications at the dihydrophthalazine edge. The co-crystal structure revealed an alternative placement of the phthalazine moiety into a shallow surface at the edge of the site that can accommodate either enantiomer of the inhibitor. The current design, therefore, highlights how to engineer specific placement of the inhibitor within this alternative pocket, which in turn maximizes the enzyme inhibitory properties of racemic mixtures.