2rda: Difference between revisions
New page: '''Unreleased structure''' The entry 2rda is ON HOLD until Paper Publication Authors: Gibson, L.M., Lovelace, L.L., Lebioda, L. Description: Human Thymidylate Synthase Stabilized in Ac... |
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{{STRUCTURE_2rda| PDB=2rda | SCENE= }} | |||
'''Human Thymidylate Synthase Stabilized in Active Conformation by R163K Mutation: Asymmetry and Reactivity of Cys195''' | |||
==Overview== | |||
Loop 181-197 of human thymidylate synthase (hTS) populates two conformational states. In the first state, Cys195, a residue crucial for catalytic activity, is in the active site (active conformer); in the other conformation, it is about 10 A away, outside the active site (inactive conformer). We have designed and expressed an hTS variant, R163K, in which the inactive conformation is destabilized. The activity of this mutant is 33% higher than that of wt hTS, suggesting that at least one-third of hTS populates the inactive conformer. Crystal structures of R163K in two different crystal forms, with six and two subunits per asymmetric part of the unit cells, have been determined. All subunits of this mutant are in the active conformation while wt hTS crystallizes as the inactive conformer in similar mother liquors. The structures show differences in the environment of catalytic Cys195, which correlate with Cys195 thiol reactivity, as judged by its oxidation state. Calculations show that the molecular electrostatic potential at Cys195 differs between the subunits of the dimer. One of the dimers is asymmetric with a phosphate ion bound in only one of the subunits. In the absence of the phosphate ion, that is in the inhibitor-free enzyme, the tip of loop 47-53 is about 11 A away from the active site. | |||
''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Wed Jun 11 | ==About this Structure== | ||
2RDA is a [[Single protein]] structure of sequence from [http://en.wikipedia.org/wiki/Homo_sapiens Homo sapiens]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=2RDA OCA]. | |||
==Reference== | |||
The R163K mutant of human thymidylate synthase is stabilized in an active conformation: structural asymmetry and reactivity of cysteine 195., Gibson LM, Lovelace LL, Lebioda L, Biochemistry. 2008 Apr 22;47(16):4636-43. Epub 2008 Mar 28. PMID:[http://www.ncbi.nlm.nih.gov/pubmed/18370400 18370400] | |||
[[Category: Homo sapiens]] | |||
[[Category: Single protein]] | |||
[[Category: Thymidylate synthase]] | |||
[[Category: Gibson, L M.]] | |||
[[Category: Lebioda, L.]] | |||
[[Category: Lovelace, L L.]] | |||
[[Category: Asymmetric]] | |||
[[Category: Methyl transferase]] | |||
[[Category: Methyltransferase]] | |||
[[Category: Nucleotide biosynthesis]] | |||
''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Wed Jun 11 10:44:46 2008'' | |||
Revision as of 10:44, 11 June 2008
Human Thymidylate Synthase Stabilized in Active Conformation by R163K Mutation: Asymmetry and Reactivity of Cys195
OverviewOverview
Loop 181-197 of human thymidylate synthase (hTS) populates two conformational states. In the first state, Cys195, a residue crucial for catalytic activity, is in the active site (active conformer); in the other conformation, it is about 10 A away, outside the active site (inactive conformer). We have designed and expressed an hTS variant, R163K, in which the inactive conformation is destabilized. The activity of this mutant is 33% higher than that of wt hTS, suggesting that at least one-third of hTS populates the inactive conformer. Crystal structures of R163K in two different crystal forms, with six and two subunits per asymmetric part of the unit cells, have been determined. All subunits of this mutant are in the active conformation while wt hTS crystallizes as the inactive conformer in similar mother liquors. The structures show differences in the environment of catalytic Cys195, which correlate with Cys195 thiol reactivity, as judged by its oxidation state. Calculations show that the molecular electrostatic potential at Cys195 differs between the subunits of the dimer. One of the dimers is asymmetric with a phosphate ion bound in only one of the subunits. In the absence of the phosphate ion, that is in the inhibitor-free enzyme, the tip of loop 47-53 is about 11 A away from the active site.
About this StructureAbout this Structure
2RDA is a Single protein structure of sequence from Homo sapiens. Full crystallographic information is available from OCA.
ReferenceReference
The R163K mutant of human thymidylate synthase is stabilized in an active conformation: structural asymmetry and reactivity of cysteine 195., Gibson LM, Lovelace LL, Lebioda L, Biochemistry. 2008 Apr 22;47(16):4636-43. Epub 2008 Mar 28. PMID:18370400 Page seeded by OCA on Wed Jun 11 10:44:46 2008