PDBsum entry 1vj3

Oxidoreductase

PDB id: 1vj3

Contents

Protein chain

205 a.a. *

Ligands

NDP

TAB

Waters ×75

* Residue conservation analysis

PDB id:

1vj3

Name:

Oxidoreductase

Title:

Structural studies on bio-active compounds. Crystal structure and molecular modeling studies on the pneumocystis carinii dihydrofolate reductase cofactor complex with tab, a highly selective antifolate.

Structure:

Dihydrofolate reductase. Chain: a. Engineered: yes

Source:

Pneumocystis carinii. Organism_taxid: 4754. Gene: c-DNA p.Carinii dhfr. Expressed in: escherichia coli. Expression_system_taxid: 562.

Resolution:

2.10Å R-factor: 0.190

Authors:

V.Cody,N.Galitsky,D.Rak,J.R.Luft,S.F.Queener,C.A.Laughton,F.G.Malcolm

Key ref:

V.Cody et al. (2000). Structural studies on bioactive compounds. 30. Crystal structure and molecular modeling studies on the Pneumocystis carinii dihydrofolate reductase cofactor complex with TAB, a highly selective antifolate. Biochemistry, 39, 3556-3564. PubMed id: 10736154 DOI: 10.1021/bi9924563

Date:

13-Jan-04 Release date: 20-Jan-04

Supersedes:

1d8r

Protein chain

P16184  (DYR_PNECA) -  Dihydrofolate reductase from Pneumocystis carinii

Seq: 206 a.a.

Struc: 205 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 = NDP) corresponds exactly) = 7,8-dihydrofolate + NADPH + H(+)

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

reference

DOI no: 10.1021/bi9924563

Biochemistry 39:3556-3564 (2000)

PubMed id: 10736154

Structural studies on bioactive compounds. 30. Crystal structure and molecular modeling studies on the Pneumocystis carinii dihydrofolate reductase cofactor complex with TAB, a highly selective antifolate.

V.Cody, D.Chan, N.Galitsky, D.Rak, J.R.Luft, W.Pangborn, S.F.Queener, C.A.Laughton, M.F.Stevens.

ABSTRACT

The crystal structure of the ternary complex of NADPH, the potent antifolate [2, 4-diamino-5-¿3-[3-(2-acetyloxyethyl)-3-benzyltriazen-1-yl]-4 -chloroph enyl¿-6-ethylpyrimidine] (TAB, 1) and Pneumocystis carinii dihydrofolate reductase (pcDHFR), refined to 2.1 A resolution, reveals that TAB binds similar to the antifolates trimethoprim and methotrexate. These data also reveal multiple conformations for the binding geometry of TAB with two preferred orientations of the acetyloxy and benzyl groups that results from a 180 degrees rotation about the N2-N3 triazenyl bond. The methyl of the acetyloxy and benzyl ring of TAB probes large hydrophobic regions of the p-aminobenzoyl folate binding pocket of the active site, in particular the region near Phe69, which is unique to the pcDHFR sequence. These results confirm prior molecular modeling investigations of the binding of TAB to pcDHFR that identified four low-energy binding geometries, two involving rotations about the terminal N(2)-N(3) triazenyl linkage and two involving atropisomerism about the pivotal pyrimethamine-phenyl bond. The primary differences in the molecular dynamics (MD) models and those observed in this crystal complex result from small conformational changes in active-site residues on energy minimization. However, two MD models place the acetyloxy and benzyl ring groups in a region of the active site between the cofactor-binding region and the p-aminobenzoyl folate pocket; an orientation never observed in any DHFR crystal structure to date. These conformers interact with solvent near the enzyme surface and are probably not observed due to the loss of specific hydrogen bonds with the enzyme. The high species pcDHFR selectivity of TAB could be the result of ligand flexibility that enables multiple binding orientations at the enzyme active site. Further modification of the acetyloxy region of TAB could increase its potency and selectivity for pcDHFR.