1wq5: Difference between revisions
New page: left|200px<br /><applet load="1wq5" size="450" color="white" frame="true" align="right" spinBox="true" caption="1wq5, resolution 2.30Å" /> '''Crystal structure of... |
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[[Image:1wq5.gif|left|200px]]<br /><applet load="1wq5" size=" | [[Image:1wq5.gif|left|200px]]<br /><applet load="1wq5" size="350" color="white" frame="true" align="right" spinBox="true" | ||
caption="1wq5, resolution 2.30Å" /> | caption="1wq5, resolution 2.30Å" /> | ||
'''Crystal structure of tryptophan synthase alpha-subunit from Escherichia coli'''<br /> | '''Crystal structure of tryptophan synthase alpha-subunit from Escherichia coli'''<br /> | ||
==Overview== | ==Overview== | ||
When the tryptophan synthase alpha- and beta(2)-subunits combine to form | When the tryptophan synthase alpha- and beta(2)-subunits combine to form the alpha(2)beta(2)-complex, the enzymatic activity of each subunit is stimulated by 1-2 orders of magnitude. To elucidate the structural basis of this mutual activation, it is necessary to determine the structures of the alpha- and beta-subunits alone and together with the alpha(2)beta(2)-complex. The crystal structures of the tryptophan synthase alpha(2)beta(2)-complex from Salmonella typhimurium (Stalpha(2)beta(2)-complex) have already been reported. However, the structures of the subunit alone from mesophiles have not yet been determined. The structure of the tryptophan synthase alpha-subunit alone from Escherichia coli (Ecalpha-subunit) was determined by an X-ray crystallographic analysis at 2.3 A, which is the first report on the subunits alone from the mesophiles. The biggest difference between the structures of the Ecalpha-subunit alone and the alpha-subunit in the Stalpha(2)beta(2)-complex (Stalpha-subunit) was as follows. Helix 2' in the Stalpha-subunit, including an active site residue (Asp60), was changed to a flexible loop in the Ecalpha-subunit alone. The conversion of the helix to a loop resulted in the collapse of the correct active site conformation. This region is also an important part for the mutual activation in the Stalpha(2)beta(2)-complex and interaction with the beta-subunit. These results suggest that the formation of helix 2'that is essential for the stimulation of the enzymatic activity of the alpha-subunit is constructed by the induced-fit mode involved in conformational changes upon interaction between the alpha- and beta-subunits. This also confirms the prediction of the conformational changes based on the thermodynamic analysis for the association between the alpha- and beta-subunits. | ||
==About this Structure== | ==About this Structure== | ||
1WQ5 is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Escherichia_coli Escherichia coli] with SO4 and GOL as [http://en.wikipedia.org/wiki/ligands ligands]. Active as [http://en.wikipedia.org/wiki/Tryptophan_synthase Tryptophan synthase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=4.2.1.20 4.2.1.20] Full crystallographic information is available from [http:// | 1WQ5 is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Escherichia_coli Escherichia coli] with <scene name='pdbligand=SO4:'>SO4</scene> and <scene name='pdbligand=GOL:'>GOL</scene> as [http://en.wikipedia.org/wiki/ligands ligands]. Active as [http://en.wikipedia.org/wiki/Tryptophan_synthase Tryptophan synthase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=4.2.1.20 4.2.1.20] Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1WQ5 OCA]. | ||
==Reference== | ==Reference== | ||
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[[Category: Nishio, K.]] | [[Category: Nishio, K.]] | ||
[[Category: Ogasahara, K.]] | [[Category: Ogasahara, K.]] | ||
[[Category: RSGI, RIKEN | [[Category: RSGI, RIKEN Structural Genomics/Proteomics Initiative.]] | ||
[[Category: Tsukihara, T.]] | [[Category: Tsukihara, T.]] | ||
[[Category: Yutani, K.]] | [[Category: Yutani, K.]] | ||
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[[Category: tryptophan synthase]] | [[Category: tryptophan synthase]] | ||
''Page seeded by [http:// | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 15:47:04 2008'' | ||
Revision as of 16:47, 21 February 2008
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Crystal structure of tryptophan synthase alpha-subunit from Escherichia coli
OverviewOverview
When the tryptophan synthase alpha- and beta(2)-subunits combine to form the alpha(2)beta(2)-complex, the enzymatic activity of each subunit is stimulated by 1-2 orders of magnitude. To elucidate the structural basis of this mutual activation, it is necessary to determine the structures of the alpha- and beta-subunits alone and together with the alpha(2)beta(2)-complex. The crystal structures of the tryptophan synthase alpha(2)beta(2)-complex from Salmonella typhimurium (Stalpha(2)beta(2)-complex) have already been reported. However, the structures of the subunit alone from mesophiles have not yet been determined. The structure of the tryptophan synthase alpha-subunit alone from Escherichia coli (Ecalpha-subunit) was determined by an X-ray crystallographic analysis at 2.3 A, which is the first report on the subunits alone from the mesophiles. The biggest difference between the structures of the Ecalpha-subunit alone and the alpha-subunit in the Stalpha(2)beta(2)-complex (Stalpha-subunit) was as follows. Helix 2' in the Stalpha-subunit, including an active site residue (Asp60), was changed to a flexible loop in the Ecalpha-subunit alone. The conversion of the helix to a loop resulted in the collapse of the correct active site conformation. This region is also an important part for the mutual activation in the Stalpha(2)beta(2)-complex and interaction with the beta-subunit. These results suggest that the formation of helix 2'that is essential for the stimulation of the enzymatic activity of the alpha-subunit is constructed by the induced-fit mode involved in conformational changes upon interaction between the alpha- and beta-subunits. This also confirms the prediction of the conformational changes based on the thermodynamic analysis for the association between the alpha- and beta-subunits.
About this StructureAbout this Structure
1WQ5 is a Single protein structure of sequence from Escherichia coli with and as ligands. Active as Tryptophan synthase, with EC number 4.2.1.20 Full crystallographic information is available from OCA.
ReferenceReference
Conformational changes in the alpha-subunit coupled to binding of the beta 2-subunit of tryptophan synthase from Escherichia coli: crystal structure of the tryptophan synthase alpha-subunit alone., Nishio K, Morimoto Y, Ishizuka M, Ogasahara K, Tsukihara T, Yutani K, Biochemistry. 2005 Feb 1;44(4):1184-92. PMID:15667212
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