1kfe: Difference between revisions
New page: left|200px<br /><applet load="1kfe" size="450" color="white" frame="true" align="right" spinBox="true" caption="1kfe, resolution 1.75Å" /> '''CRYSTAL STRUCTURE OF... |
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[[Image:1kfe.jpg|left|200px]]<br /><applet load="1kfe" size=" | [[Image:1kfe.jpg|left|200px]]<br /><applet load="1kfe" size="350" color="white" frame="true" align="right" spinBox="true" | ||
caption="1kfe, resolution 1.75Å" /> | caption="1kfe, resolution 1.75Å" /> | ||
'''CRYSTAL STRUCTURE OF ALPHAT183V MUTANT OF TRYPTOPHAN SYNTHASE FROM SALMONELLA TYPHIMURIUM WITH L-Ser Bound To The Beta Site'''<br /> | '''CRYSTAL STRUCTURE OF ALPHAT183V MUTANT OF TRYPTOPHAN SYNTHASE FROM SALMONELLA TYPHIMURIUM WITH L-Ser Bound To The Beta Site'''<br /> | ||
==Overview== | ==Overview== | ||
The catalytic activity and substrate channeling of the pyridoxal | The catalytic activity and substrate channeling of the pyridoxal 5'-phosphate-dependent tryptophan synthase alpha(2)beta(2) complex is regulated by allosteric interactions that modulate the switching of the enzyme between open, low activity and closed, high activity states during the catalytic cycle. The highly conserved alphaThr183 residue is part of loop alphaL6 and is located next to the alpha-active site and forms part of the alpha-beta subunit interface. The role of the interactions of alphaThr183 in alpha-site catalysis and allosteric regulation was investigated by analyzing the kinetics and crystal structures of the isosteric mutant alphaThr183Val. The mutant displays strongly impaired allosteric alpha-beta communication, and the catalytic activity of the alpha-reaction is reduced one hundred fold, whereas the beta-activity is not affected. The structural work establishes that the basis for the missing inter-subunit signaling is the lack of loop alphaL6 closure even in the presence of the alpha-subunit ligands, 3-indolyl-D-glycerol 3'-phosphate, or 3-indolylpropanol 3'-phosphate. The structural basis for the reduced alpha-activity has its origins in the missing hydrogen bond between alphaThr183 and the catalytic residue, alphaAsp60. | ||
==About this Structure== | ==About this Structure== | ||
1KFE is a [http://en.wikipedia.org/wiki/Protein_complex Protein complex] structure of sequences from [http://en.wikipedia.org/wiki/Salmonella_typhimurium Salmonella typhimurium] and [http://en.wikipedia.org/wiki/Salmonella_typhimurium_lt2 Salmonella typhimurium lt2] with NA and PLS as [http://en.wikipedia.org/wiki/ligands ligands]. Full crystallographic information is available from [http:// | 1KFE is a [http://en.wikipedia.org/wiki/Protein_complex Protein complex] structure of sequences from [http://en.wikipedia.org/wiki/Salmonella_typhimurium Salmonella typhimurium] and [http://en.wikipedia.org/wiki/Salmonella_typhimurium_lt2 Salmonella typhimurium lt2] with <scene name='pdbligand=NA:'>NA</scene> and <scene name='pdbligand=PLS:'>PLS</scene> as [http://en.wikipedia.org/wiki/ligands ligands]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1KFE OCA]. | ||
==Reference== | ==Reference== | ||
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[[Category: Salmonella typhimurium lt2]] | [[Category: Salmonella typhimurium lt2]] | ||
[[Category: Arac, D.]] | [[Category: Arac, D.]] | ||
[[Category: Dunn, M | [[Category: Dunn, M F.]] | ||
[[Category: Kulik, V.]] | [[Category: Kulik, V.]] | ||
[[Category: Niks, D.]] | [[Category: Niks, D.]] | ||
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[[Category: helix]] | [[Category: helix]] | ||
''Page seeded by [http:// | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 13:33:35 2008'' | ||
Revision as of 14:33, 21 February 2008
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CRYSTAL STRUCTURE OF ALPHAT183V MUTANT OF TRYPTOPHAN SYNTHASE FROM SALMONELLA TYPHIMURIUM WITH L-Ser Bound To The Beta Site
OverviewOverview
The catalytic activity and substrate channeling of the pyridoxal 5'-phosphate-dependent tryptophan synthase alpha(2)beta(2) complex is regulated by allosteric interactions that modulate the switching of the enzyme between open, low activity and closed, high activity states during the catalytic cycle. The highly conserved alphaThr183 residue is part of loop alphaL6 and is located next to the alpha-active site and forms part of the alpha-beta subunit interface. The role of the interactions of alphaThr183 in alpha-site catalysis and allosteric regulation was investigated by analyzing the kinetics and crystal structures of the isosteric mutant alphaThr183Val. The mutant displays strongly impaired allosteric alpha-beta communication, and the catalytic activity of the alpha-reaction is reduced one hundred fold, whereas the beta-activity is not affected. The structural work establishes that the basis for the missing inter-subunit signaling is the lack of loop alphaL6 closure even in the presence of the alpha-subunit ligands, 3-indolyl-D-glycerol 3'-phosphate, or 3-indolylpropanol 3'-phosphate. The structural basis for the reduced alpha-activity has its origins in the missing hydrogen bond between alphaThr183 and the catalytic residue, alphaAsp60.
About this StructureAbout this Structure
1KFE is a Protein complex structure of sequences from Salmonella typhimurium and Salmonella typhimurium lt2 with and as ligands. Full crystallographic information is available from OCA.
ReferenceReference
On the role of alphaThr183 in the allosteric regulation and catalytic mechanism of tryptophan synthase., Kulik V, Weyand M, Seidel R, Niks D, Arac D, Dunn MF, Schlichting I, J Mol Biol. 2002 Dec 6;324(4):677-90. PMID:12460570
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