PMID: 9535826May 16, 1998Paper

Cryo-crystallography of a true substrate, indole-3-glycerol phosphate, bound to a mutant (alphaD60N) tryptophan synthase alpha2beta2 complex reveals the correct orientation of active site alphaGlu49.

The Journal of Biological Chemistry
S RheeD R Davies

Abstract

The reversible cleavage of indole-3-glycerol by the alpha-subunit of tryptophan synthase has been proposed to be catalyzed by alphaGlu49 and alphaAsp60. Although previous x-ray crystallographic structures of the tryptophan synthase alpha2beta2 complex showed an interaction between the carboxylate of alphaAsp60 and the bound inhibitor indole-3-propanol phosphate, the carboxylate of alphaGlu49 was too distant to play its proposed role. To clarify the structural and functional roles of alphaGlu49, we have determined crystal structures of a mutant (alphaD60N) alpha2beta2 complex in the presence and absence of the true substrate, indole-3-glycerol phosphate. The enzyme in the crystal cleaves indole-3-glycerol phosphate very slowly at room temperature but not under cryo-conditions of 95 K. The structure of the complex with the true substrate obtained by cryo-crystallography reveals that indole-3-glycerol phosphate and indole-3-propanol phosphate have similar binding modes but different torsion angles. Most importantly, the side chain of alphaGlu49 interacts with 3-hydroxyl group of indole-3-glycerol phosphate as proposed. The movement of the side chain of alphaGlu49 into an extended conformation upon binding the true substrate provid...Continue Reading

Citations

Jan 23, 1999·Current Opinion in Structural Biology·J N Jansonius
Nov 18, 1998·Current Opinion in Structural Biology·B L Stoddard
Apr 29, 2014·Journal of the American Chemical Society·Jennifer M AxeDavid D Boehr
Mar 30, 2001·The Journal of Biological Chemistry·A MarabottiA Mozzarelli
Nov 17, 2006·Chemical Record : an Official Publication of the Chemical Society of Japan ... [et Al.]·Andrea Mozzarelli, Stefano Bettati
Jan 5, 2002·The Journal of Biological Chemistry·Michael WeyandAndrea Mozzarelli
Jan 5, 2002·The Journal of Biological Chemistry·Michael WeyandAndrea Mozzarelli
Apr 23, 1999·The Journal of Biological Chemistry·E W MilesD R Davies

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