3S7A

Human dihydrofolate reductase binary complex with PT684

Summary for 3S7A

• Entry DOI: 10.2210/pdb3s7a/pdb
• Descriptor: Dihydrofolate reductase, SULFATE ION, 4-({5-[(2,4-diaminopteridin-6-yl)methyl]-5H-dibenzo[b,f]azepin-2-yl}oxy)butanoic acid, ... (4 entities in total)
• Functional Keywords: single polypeptide chain, reductase, oxidoreductase-oxidoreductase inhibitor complex, oxidoreductase/oxidoreductase inhibitor
• Biological source: Homo sapiens (human)
• Total number of polymer chains: 1
• Total formula weight: 22299.33

Authors

Cody, V.,Pace, J.,Nowak, J. (deposition date: 2011-05-26, release date: 2011-10-05, Last modification date: 2023-09-13)

Primary citation

Cody, V.,Pace, J.,Nowak, J.
Structural analysis of human dihydrofolate reductase as a binary complex with the potent and selective inhibitor 2,4-diamino-6-{2'-O-(3-carboxypropyl)oxydibenz[b,f]-azepin-5-yl}methylpteridine reveals an unusual binding mode.
Acta Crystallogr.,Sect.D, 67:875-880, 2011

PubMed Abstract: In order to understand the structure-activity profile observed for a series of substituted dibenz[b,f]azepine antifolates, the crystal structure of the binary complex of human dihydrofolate reductase (hDHFR) with the potent and selective inhibitor 2,4-diamino-6-{2'-O-(3-carboxypropyl)oxydibenz[b,f]-azepin-5-yl}methylpteridine (PT684) was determined to 1.8 Å resolution. These data revealed that the carboxylate side chain of PT684 occupies two alternate positions, neither of which interacts with the conserved Arg70 in the active-site pocket, which in turn hydrogen bonds to water. These observations are in contrast to those reported for the ternary complex of mouse DHFR (mDHFR) with NADPH [Cody et al. (2008), Acta Cryst. D64, 977-984], in which the 3-carboxypropyl side chain of PT684 was hydrolyzed to its hydroxyl derivative, PT684a. The crystallization conditions differed for the human and mouse DHFR crystals (100 mM K2HPO4 pH 6.9, 30% ammonium sulfate for hDHFR; 15 mM Tris pH 8.3, 75 mM sodium cacodylate, PEG 4K for mDHFR). Additionally, the side chains of Phe31 and Gln35 in the hDHFR complex have a single conformation, whereas in the mDHFR complex they occupied two alternative conformations. These data show that the hDHFR complex has a decreased active-site volume compared with the mDHFR complex, as reflected in a relative shift of helix C (residues 59-64) of 1.2 Å, and a shift of 1.5 Å compared with the ternary complex of Pneumocystis carinii DHFR (pcDHFR) with the parent dibenz[b,f]azepine PT653. These data suggest that the greater inhibitory potency of PT684 against pcDHFR is consistent with the larger active-site volume of pcDHFR and the predicted interactions of the carboxylate side chain with Arg75.

PubMed: 21931219
DOI: 10.1107/S0907444911030071

Experimental method

X-RAY DIFFRACTION (1.8 Å)