Tags

Type your tag names separated by a space and hit enter

Crystal structures of a mutant (betaK87T) tryptophan synthase alpha2beta2 complex with ligands bound to the active sites of the alpha- and beta-subunits reveal ligand-induced conformational changes.
Biochemistry. 1997 Jun 24; 36(25):7664-80.B

Abstract

Three-dimensional structures are reported for a mutant (betaK87T) tryptophan synthase alpha2beta2 complex with either the substrate L-serine (betaK87T-Ser) or product L-tryptophan (betaK87T-Trp) at the active site of the beta-subunit, in which both amino acids form external aldimines with the coenzyme, pyridoxal phosphate. We also present structures with L-serine bound to the beta site and either alpha-glycerol 3-phosphate (betaK87T-Ser-GP) or indole-3-propanol phosphate (betaK87T-Ser-IPP) bound to the active site of the alpha-subunit. The results further identify the substrate and product binding sites in each subunit and provide insight into conformational changes that occur upon formation of these complexes. The two structures having ligands at the active sites of both alpha- and beta-subunits reveal an important new feature, the ordering of alpha-subunit loop 6 (residues 179-187). Closure of loop 6 isolates the active site of the alpha-subunit from solvent and results in interaction between alphaThr183 and the catalytic residue alphaAsp60. Other conformational differences between the wild type and these two mutant structures include a rigid-body rotation of the alpha-subunit of approximately 5 degrees relative to the beta-subunit and large movements of part of the beta-subunit (residues 93-189) toward the rest of the beta-subunit. Much smaller differences are observed in the betaK87T-Ser structure. Remarkably, binding of tryptophan to the beta active site results in conformational changes very similar to those observed in the betaK87T-Ser-GP and betaK87T-Ser-IPP structures, with exception of the disordered alpha-subunit loop 6. These large-scale changes, the closure of loop 6, and the movements of a small number of side chains in the alpha-beta interaction site provide a structural base for interpreting the allosteric properties of tryptophan synthase.

Authors+Show Affiliations

Laboratory of Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland 20892, USA.No affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article

Language

eng

PubMed ID

9201907

Citation

Rhee, S, et al. "Crystal Structures of a Mutant (betaK87T) Tryptophan Synthase Alpha2beta2 Complex With Ligands Bound to the Active Sites of the Alpha- and Beta-subunits Reveal Ligand-induced Conformational Changes." Biochemistry, vol. 36, no. 25, 1997, pp. 7664-80.
Rhee S, Parris KD, Hyde CC, et al. Crystal structures of a mutant (betaK87T) tryptophan synthase alpha2beta2 complex with ligands bound to the active sites of the alpha- and beta-subunits reveal ligand-induced conformational changes. Biochemistry. 1997;36(25):7664-80.
Rhee, S., Parris, K. D., Hyde, C. C., Ahmed, S. A., Miles, E. W., & Davies, D. R. (1997). Crystal structures of a mutant (betaK87T) tryptophan synthase alpha2beta2 complex with ligands bound to the active sites of the alpha- and beta-subunits reveal ligand-induced conformational changes. Biochemistry, 36(25), 7664-80.
Rhee S, et al. Crystal Structures of a Mutant (betaK87T) Tryptophan Synthase Alpha2beta2 Complex With Ligands Bound to the Active Sites of the Alpha- and Beta-subunits Reveal Ligand-induced Conformational Changes. Biochemistry. 1997 Jun 24;36(25):7664-80. PubMed PMID: 9201907.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Crystal structures of a mutant (betaK87T) tryptophan synthase alpha2beta2 complex with ligands bound to the active sites of the alpha- and beta-subunits reveal ligand-induced conformational changes. AU - Rhee,S, AU - Parris,K D, AU - Hyde,C C, AU - Ahmed,S A, AU - Miles,E W, AU - Davies,D R, PY - 1997/6/24/pubmed PY - 1997/6/24/medline PY - 1997/6/24/entrez SP - 7664 EP - 80 JF - Biochemistry JO - Biochemistry VL - 36 IS - 25 N2 - Three-dimensional structures are reported for a mutant (betaK87T) tryptophan synthase alpha2beta2 complex with either the substrate L-serine (betaK87T-Ser) or product L-tryptophan (betaK87T-Trp) at the active site of the beta-subunit, in which both amino acids form external aldimines with the coenzyme, pyridoxal phosphate. We also present structures with L-serine bound to the beta site and either alpha-glycerol 3-phosphate (betaK87T-Ser-GP) or indole-3-propanol phosphate (betaK87T-Ser-IPP) bound to the active site of the alpha-subunit. The results further identify the substrate and product binding sites in each subunit and provide insight into conformational changes that occur upon formation of these complexes. The two structures having ligands at the active sites of both alpha- and beta-subunits reveal an important new feature, the ordering of alpha-subunit loop 6 (residues 179-187). Closure of loop 6 isolates the active site of the alpha-subunit from solvent and results in interaction between alphaThr183 and the catalytic residue alphaAsp60. Other conformational differences between the wild type and these two mutant structures include a rigid-body rotation of the alpha-subunit of approximately 5 degrees relative to the beta-subunit and large movements of part of the beta-subunit (residues 93-189) toward the rest of the beta-subunit. Much smaller differences are observed in the betaK87T-Ser structure. Remarkably, binding of tryptophan to the beta active site results in conformational changes very similar to those observed in the betaK87T-Ser-GP and betaK87T-Ser-IPP structures, with exception of the disordered alpha-subunit loop 6. These large-scale changes, the closure of loop 6, and the movements of a small number of side chains in the alpha-beta interaction site provide a structural base for interpreting the allosteric properties of tryptophan synthase. SN - 0006-2960 UR - https://www.unboundmedicine.com/medline/citation/9201907/Crystal_structures_of_a_mutant__betaK87T__tryptophan_synthase_alpha2beta2_complex_with_ligands_bound_to_the_active_sites_of_the_alpha__and_beta_subunits_reveal_ligand_induced_conformational_changes_ L2 - https://doi.org/10.1021/bi9700429 DB - PRIME DP - Unbound Medicine ER -