1cz3
From Proteopedia
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DIHYDROFOLATE REDUCTASE FROM THERMOTOGA MARITIMA
Overview
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.
About this Structure
1CZ3 is a Single protein structure of sequence from Thermotoga maritima with SO4 as ligand. Active as Dihydrofolate reductase, with EC number 1.5.1.3 Full crystallographic information is available from OCA.
Reference
The crystal structure of dihydrofolate reductase from Thermotoga maritima: molecular features of thermostability., Dams T, Auerbach G, Bader G, Jacob U, Ploom T, Huber R, Jaenicke R, J Mol Biol. 2000 Mar 31;297(3):659-72. PMID:10731419
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