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1v7y
From Proteopedia
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'''Crystal structure of tryptophan synthase alpha-subunit from Escherichia coli at room temperature''' | '''Crystal structure of tryptophan synthase alpha-subunit from Escherichia coli at room temperature''' | ||
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[[Category: Tsukihara, T.]] | [[Category: Tsukihara, T.]] | ||
[[Category: Yutani, K.]] | [[Category: Yutani, K.]] | ||
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| - | [[Category: | + | [[Category: Rsgi]] |
| - | [[Category: | + | [[Category: Structural genomic]] |
| - | [[Category: | + | [[Category: Tryptophan]] |
| - | [[Category: | + | [[Category: Tryptophan synthase]] |
| - | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Sat May 3 12:11:45 2008'' | |
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Revision as of 09:11, 3 May 2008
Crystal structure of tryptophan synthase alpha-subunit from Escherichia coli at room temperature
Overview
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
1V7Y is a Single protein structure of sequence from Escherichia coli. Full crystallographic information is available from OCA.
Reference
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 Page seeded by OCA on Sat May 3 12:11:45 2008
Categories: Escherichia coli | Single protein | Tryptophan synthase | Ishizuka, M. | Morimoto, Y. | Nishio, K. | Ogasahara, K. | RSGI, RIKEN Structural Genomics/Proteomics Initiative. | Tsukihara, T. | Yutani, K. | Riken structural genomics/proteomics initiative | Rsgi | Structural genomic | Tryptophan
