1bo8: Difference between revisions
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[[Image:1bo8.gif|left|200px]] | [[Image:1bo8.gif|left|200px]] | ||
'''THYMIDYLATE SYNTHASE R178T MUTANT''' | {{Structure | ||
|PDB= 1bo8 |SIZE=350|CAPTION= <scene name='initialview01'>1bo8</scene>, resolution 2.40Å | |||
|SITE= | |||
|LIGAND= <scene name='pdbligand=K:POTASSIUM+ION'>K</scene> and <scene name='pdbligand=U:URIDINE-5'-MONOPHOSPHATE'>U</scene> | |||
|ACTIVITY= [http://en.wikipedia.org/wiki/Thymidylate_synthase Thymidylate synthase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=2.1.1.45 2.1.1.45] | |||
|GENE= | |||
}} | |||
'''THYMIDYLATE SYNTHASE R178T MUTANT''' | |||
==Overview== | ==Overview== | ||
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==About this Structure== | ==About this Structure== | ||
1BO8 is a [ | 1BO8 is a [[Single protein]] structure of sequence from [http://en.wikipedia.org/wiki/Lactobacillus_casei Lactobacillus casei]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1BO8 OCA]. | ||
==Reference== | ==Reference== | ||
Energetic contributions of four arginines to phosphate-binding in thymidylate synthase are more than additive and depend on optimization of "effective charge balance"., Morse RJ, Kawase S, Santi DV, Finer-Moore J, Stroud RM, Biochemistry. 2000 Feb 8;39(5):1011-20. PMID:[http:// | Energetic contributions of four arginines to phosphate-binding in thymidylate synthase are more than additive and depend on optimization of "effective charge balance"., Morse RJ, Kawase S, Santi DV, Finer-Moore J, Stroud RM, Biochemistry. 2000 Feb 8;39(5):1011-20. PMID:[http://www.ncbi.nlm.nih.gov/pubmed/10653645 10653645] | ||
[[Category: Lactobacillus casei]] | [[Category: Lactobacillus casei]] | ||
[[Category: Single protein]] | [[Category: Single protein]] | ||
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[[Category: transferase (methyltransferase)]] | [[Category: transferase (methyltransferase)]] | ||
''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Mar 20 10:13:37 2008'' | ||
Revision as of 11:13, 20 March 2008
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| , resolution 2.40Å | |||||||
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| Ligands: | and | ||||||
| Activity: | Thymidylate synthase, with EC number 2.1.1.45 | ||||||
| Coordinates: | save as pdb, mmCIF, xml | ||||||
THYMIDYLATE SYNTHASE R178T MUTANT
OverviewOverview
In thymidylate synthase, four conserved arginines provide two hydrogen bonds each to the oxygens of the phosphate group of the substrate, 2'-deoxyuridine-5'-monophosphate. Of these, R23, R178, and R179 are far removed from the site of methyl transfer and contribute to catalysis solely through binding and orientation of ligands. These arginines can be substituted by other residues, while still retaining more than 1% activity of the wild-type enzyme. We compared the kinetics and determined the crystal structures of dUMP complexes of three of the most active, uncharged single mutants of these arginines, R23I, R178T, and R179T, and of double mutants (R23I, R179T) and (R178T, R179T). The dramatically higher K(m) for R178T compared to the other two single mutants arises from the effects of R178 substitution on the orientation of dUMP; 10-15-fold increases in for R23I and R178T reflect the role of these residues in stabilizing the closed conformation of TS in ternary complexes. The free energy for productive dUMP binding, DeltaG(S), increases by at least 1 kcal/mol for each mutant, even when dUMP orientation and mobility in the crystal structure is the same as in wild-type enzyme. Thus, the four arginines do not contribute excess positive charge to the PO(4)(-2) binding site; rather, they ideally complement the charge and geometry of the phosphate moiety. More-than-additive increases in DeltaG(S) seen in the double mutants are consistent with quadratic increases in DeltaG(S) predicted for deviations from ideal electrostatic interactions and may also reflect cooperative binding of the arginines to the phosphate oxygens.
About this StructureAbout this Structure
1BO8 is a Single protein structure of sequence from Lactobacillus casei. Full crystallographic information is available from OCA.
ReferenceReference
Energetic contributions of four arginines to phosphate-binding in thymidylate synthase are more than additive and depend on optimization of "effective charge balance"., Morse RJ, Kawase S, Santi DV, Finer-Moore J, Stroud RM, Biochemistry. 2000 Feb 8;39(5):1011-20. PMID:10653645
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