title: Subunit communication in the tryptophan synthase alpha 2 beta 2 complex. Effects of beta subunit ligands on proteolytic cleavage of a flexible loop in the alpha subunit.
abstract: To probe the structural basis for ligand-mediated communication between the alpha and beta subunits in the tryptophan synthase alpha 2 beta 2 complex, we have determined the effects of ligands of the alpha and beta subunits on proteolysis of a flexible loop in the alpha subunit. We find that addition of a ligand of the beta subunit (L-serine, D-tryptophan, or L-tryptophan) in combination with a ligand of the alpha subunit (alpha-glycerol 3-phosphate) almost completely prevents the tryptic cleavage of the alpha subunit loop. Thus, the binding of a ligand to the beta-site affects the conformation of the alpha subunit 25-30 A distant.
authors.affiliation: Laboratory of Biochemical Pharmacology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892.
authors.forename: S B
authors.initials: SB
authors.lastname: Ruvinov
authors.forename: E W
authors.initials: EW
authors.lastname: Miles
mesh_terms: D004591:Electrophoresis, Polyacrylamide Gel; D006868:Hydrolysis; D007527:Isoenzymes / Q000378:metabolism; D011487:Protein Conformation; D012486:Salmonella typhimurium / Q000201:enzymology; D014367:Tryptophan Synthase / Q000378:metabolism*
chemical_list: D007527:Isoenzymes; D014367:Tryptophan Synthase