1CZ3

DIHYDROFOLATE REDUCTASE FROM THERMOTOGA MARITIMA

Summary for 1CZ3

• Entry DOI: 10.2210/pdb1cz3/pdb
• Descriptor: DIHYDROFOLATE REDUCTASE, SULFATE ION (3 entities in total)
• Functional Keywords: dimer, hyperthermophile, oxidoreductase
• Biological source: Thermotoga maritima
• Total number of polymer chains: 2
• Total formula weight: 38718.70

Authors

Dams, T.,Auerbach, G.,Bader, G.,Ploom, T.,Huber, R.,Jaenicke, R. (deposition date: 1999-09-01, release date: 2000-03-31, Last modification date: 2024-02-07)

Primary citation

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.
J.Mol.Biol., 297:659-672, 2000

PubMed 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.

PubMed: 10731419
DOI: 10.1006/jmbi.2000.3570

Experimental method

X-RAY DIFFRACTION (2.1 Å)