1V7Y

Crystal structure of tryptophan synthase alpha-subunit from Escherichia coli at room temperature

Summary for 1V7Y

• Entry DOI: 10.2210/pdb1v7y/pdb
• Related: 1WQ5
• Descriptor: Tryptophan synthase alpha chain, SULFATE ION (3 entities in total)
• Functional Keywords: tryptophan synthase, tryptophan, riken structural genomics/proteomics initiative, rsgi, structural genomics, lyase
• Biological source: Escherichia coli
• Total number of polymer chains: 2
• Total formula weight: 57696.31

Authors

Nishio, K.,Morimoto, Y.,Ishizuka, M.,Ogasahara, K.,Yutani, K.,Tsukihara, T.,RIKEN Structural Genomics/Proteomics Initiative (RSGI) (deposition date: 2003-12-25, release date: 2005-02-15, Last modification date: 2023-12-27)

Primary citation

Nishio, K.,Morimoto, Y.,Ishizuka, M.,Ogasahara, K.,Tsukihara, T.,Yutani, K.
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 Alon
Biochemistry, 44:1184-1192, 2005

PubMed Abstract: 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.

PubMed: 15667212
DOI: 10.1021/bi047927m

Experimental method

X-RAY DIFFRACTION (2.5 Å)