1dig: Difference between revisions
New page: left|200px<br /> <applet load="1dig" size="450" color="white" frame="true" align="right" spinBox="true" caption="1dig, resolution 2.2Å" /> '''HUMAN METHYLENETETRA... |
No edit summary |
||
| Line 1: | Line 1: | ||
[[Image:1dig.gif|left|200px]]<br /> | [[Image:1dig.gif|left|200px]]<br /><applet load="1dig" size="350" color="white" frame="true" align="right" spinBox="true" | ||
<applet load="1dig" size=" | |||
caption="1dig, resolution 2.2Å" /> | caption="1dig, resolution 2.2Å" /> | ||
'''HUMAN METHYLENETETRAHYDROFOLATE DEHYDROGENASE / CYCLOHYDROLASE COMPLEXED WITH NADP AND INHIBITOR LY374571'''<br /> | '''HUMAN METHYLENETETRAHYDROFOLATE DEHYDROGENASE / CYCLOHYDROLASE COMPLEXED WITH NADP AND INHIBITOR LY374571'''<br /> | ||
==Overview== | ==Overview== | ||
Enzymes involved in tetrahydrofolate metabolism are of particular | Enzymes involved in tetrahydrofolate metabolism are of particular pharmaceutical interest, as their function is crucial for amino acid and DNA biosynthesis. The crystal structure of the human cytosolic methylenetetrahydrofolate dehydrogenase/cyclohydrolase (DC301) domain of a trifunctional enzyme has been determined previously with a bound NADP cofactor. While the substrate binding site was identified to be localized in a deep and rather hydrophobic cleft at the interface between two protein domains, the unambiguous assignment of catalytic residues was not possible. We succeeded in determining the crystal structures of three ternary DC301/NADP/inhibitor complexes. Investigation of these structures followed by site-directed mutagenesis studies allowed identification of the amino acids involved in catalysis by both enzyme activities. The inhibitors bind close to Lys56 and Tyr52, residues of a strictly conserved motif for active sites in dehydrogenases. While Lys56 is in a good position for chemical interaction with the substrate analogue, Tyr52 was found stacking against the inhibitors' aromatic rings and hence seems to be more important for proper positioning of the ligand than for catalysis. Also, Ser49 and/or Cys147 were found to possibly act as an activator for water in the cyclohydrolase step. These and the other residues (Gln100 and Asp125), with which contacts are made, are strictly conserved in THF dehydrogenases. On the basis of structural and mutagenesis data, we propose a reaction mechanism for both activities, the dehydrogenase and the cyclohydrolase. | ||
==Disease== | ==Disease== | ||
| Line 11: | Line 10: | ||
==About this Structure== | ==About this Structure== | ||
1DIG is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Homo_sapiens Homo sapiens] with ACT, NAP and L37 as [http://en.wikipedia.org/wiki/ligands ligands]. Full crystallographic information is available from [http:// | 1DIG is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Homo_sapiens Homo sapiens] with <scene name='pdbligand=ACT:'>ACT</scene>, <scene name='pdbligand=NAP:'>NAP</scene> and <scene name='pdbligand=L37:'>L37</scene> as [http://en.wikipedia.org/wiki/ligands ligands]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1DIG OCA]. | ||
==Reference== | ==Reference== | ||
| Line 17: | Line 16: | ||
[[Category: Homo sapiens]] | [[Category: Homo sapiens]] | ||
[[Category: Single protein]] | [[Category: Single protein]] | ||
[[Category: Bewly, J | [[Category: Bewly, J R.]] | ||
[[Category: Chen, V | [[Category: Chen, V J.]] | ||
[[Category: Cygler, M.]] | [[Category: Cygler, M.]] | ||
[[Category: MacKenzie, R | [[Category: MacKenzie, R E.]] | ||
[[Category: Ray, J | [[Category: Ray, J E.]] | ||
[[Category: Schmidt, A.]] | [[Category: Schmidt, A.]] | ||
[[Category: Toth, J | [[Category: Toth, J E.]] | ||
[[Category: Wu, H.]] | [[Category: Wu, H.]] | ||
[[Category: ACT]] | [[Category: ACT]] | ||
| Line 35: | Line 34: | ||
[[Category: tetrahydrofolate]] | [[Category: tetrahydrofolate]] | ||
''Page seeded by [http:// | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 12:16:57 2008'' | ||
Revision as of 13:16, 21 February 2008
|
HUMAN METHYLENETETRAHYDROFOLATE DEHYDROGENASE / CYCLOHYDROLASE COMPLEXED WITH NADP AND INHIBITOR LY374571
OverviewOverview
Enzymes involved in tetrahydrofolate metabolism are of particular pharmaceutical interest, as their function is crucial for amino acid and DNA biosynthesis. The crystal structure of the human cytosolic methylenetetrahydrofolate dehydrogenase/cyclohydrolase (DC301) domain of a trifunctional enzyme has been determined previously with a bound NADP cofactor. While the substrate binding site was identified to be localized in a deep and rather hydrophobic cleft at the interface between two protein domains, the unambiguous assignment of catalytic residues was not possible. We succeeded in determining the crystal structures of three ternary DC301/NADP/inhibitor complexes. Investigation of these structures followed by site-directed mutagenesis studies allowed identification of the amino acids involved in catalysis by both enzyme activities. The inhibitors bind close to Lys56 and Tyr52, residues of a strictly conserved motif for active sites in dehydrogenases. While Lys56 is in a good position for chemical interaction with the substrate analogue, Tyr52 was found stacking against the inhibitors' aromatic rings and hence seems to be more important for proper positioning of the ligand than for catalysis. Also, Ser49 and/or Cys147 were found to possibly act as an activator for water in the cyclohydrolase step. These and the other residues (Gln100 and Asp125), with which contacts are made, are strictly conserved in THF dehydrogenases. On the basis of structural and mutagenesis data, we propose a reaction mechanism for both activities, the dehydrogenase and the cyclohydrolase.
DiseaseDisease
Known diseases associated with this structure: Abruptio placentae, susceptibility to OMIM:[172460], Spina bifida, folate-sensitive, susceptibility to OMIM:[172460]
About this StructureAbout this Structure
1DIG is a Single protein structure of sequence from Homo sapiens with , and as ligands. Full crystallographic information is available from OCA.
ReferenceReference
Structures of three inhibitor complexes provide insight into the reaction mechanism of the human methylenetetrahydrofolate dehydrogenase/cyclohydrolase., Schmidt A, Wu H, MacKenzie RE, Chen VJ, Bewly JR, Ray JE, Toth JE, Cygler M, Biochemistry. 2000 May 30;39(21):6325-35. PMID:10828945
Page seeded by OCA on Thu Feb 21 12:16:57 2008