Database accession: MF2120026
Name: Dihydrofolate reductase
PDB ID: 1cz3
Experimental method: X-ray (2.10 Å)
Assembly: homodimer
Source organism: Thermotoga maritima
Primer publication of the structure:
Dams T, Auerbach G, Bader G, Jacob U, Ploom T, Huber R, Jaenicke R
The crystal structure of dihydrofolate reductase from Thermotoga maritima: molecular features of thermostability.
(2000) J. Mol. Biol. 297: 659-72
PMID: 10731419
Abstract:
Two high-resolution structures have been obtained for dihydrofolate reductase from the hyperthermophilic bacterium Thermotoga maritima in its unliganded state, and in its ternary complex with the cofactor NADPH and the inhibitor, methotrexate. While the overall fold of the hyperthermophilic enzyme is closely similar to monomeric mesophilic dihydrofolate reductase molecules, its quaternary structure is exceptional, in that T. maritima dihydrofolate reductase forms a highly stable homodimer. Here, the molecular reasons for the high intrinsic stability of the enzyme are elaborated and put in context with the available data on the physical parameters governing the folding reaction. The molecule is extremely rigid, even with respect to structural changes during substrate binding and turnover. Subunit cooperativity can be excluded from structural and biochemical data. Major contributions to the high intrinsic stability of the enzyme result from the formation of the dimer. Within the monomer, only subtle stabilizing interactions are detectable, without clear evidence for any of the typical increments of thermal stabilization commonly reported for hyperthermophilic proteins. The docking of the subunits is optimized with respect to high packing density in the dimer interface, additional salt-bridges and beta-sheets. The enzyme does not show significant structural changes upon binding its coenzyme, NADPH, and the inhibitor, methotrexate. The active-site loop, which is known to play an important role in catalysis in mesophilic dihydrofolate reductase molecules, is rearranged, participating in the association of the subunits; it no longer participates in catalysis.
Molecular function:
dihydrofolate reductase activity Catalysis of the reaction: 5,6,7,8-tetrahydrofolate + NADP+ = 7,8-dihydrofolate + NADPH + H+.
Biological process:
oxidation-reduction process A metabolic process that results in the removal or addition of one or more electrons to or from a substance, with or without the concomitant removal or addition of a proton or protons.
glycine biosynthetic process The chemical reactions and pathways resulting in the formation of glycine, aminoethanoic acid.
one-carbon metabolic process The chemical reactions and pathways involving the transfer of one-carbon units in various oxidation states.
tetrahydrofolate biosynthetic process The chemical reactions and pathways resulting in the formation of tetrahydrofolate, 5,6,7,8-tetrahydrofolic acid, a folate derivative bearing additional hydrogens on the pterin group.
Cellular component: not assigned
Entry contents: 2 distinct polypeptide molecules
Chains: A, B
Notes: No modifications of the original PDB file. Chain identifiers are identical with the PDB's identifiers.
Number of unique protein segments: 1
Name: Dihydrofolate reductase
Source organism: Thermotoga maritima
Length: 164 residues
Sequence:Sequence according to PDB SEQRESAKVIFVLAMDVSGKIASSVESWSSFEDRKNFRKITTEIGNVVMGRITFEEIGRPLPERLNVVLTRRPKTSNNPSLVFFNGSPADVVKFLEGKGYERVAVIGGKTVFTEFLREKLVDELFVTVEPYVFGKGIPFFDEFEGYFPLKLLEMRRLNERGTLFLKYSVE
UniProtKB AC: Q60034 (positions: 2-165)
Coverage: 97%UniRef90 AC: UniRef90_Q60034 (positions: 2-165)
Name: Dihydrofolate reductase
Source organism: Thermotoga maritima
Length: 164 residues
Sequence:Sequence according to PDB SEQRESAKVIFVLAMDVSGKIASSVESWSSFEDRKNFRKITTEIGNVVMGRITFEEIGRPLPERLNVVLTRRPKTSNNPSLVFFNGSPADVVKFLEGKGYERVAVIGGKTVFTEFLREKLVDELFVTVEPYVFGKGIPFFDEFEGYFPLKLLEMRRLNERGTLFLKYSVE
UniProtKB AC: Q60034 (positions: 2-165)
Coverage: 97%UniRef90 AC: UniRef90_Q60034 (positions: 2-165)
Complex evidence:
The enzyme DHFR from the hyperthermophilic bacterium Thermotoga maritima represents an extremely stable dimer; no isolated structured monomers could be detected in equilibrium or during unfolding. The equilibrium unfolding strictly follows the two-state model for the dimer (PMID: 10413491).