1BEU

TRP SYNTHASE (D60N-IPP-SER) WITH K+

Summary for 1BEU

• Entry DOI: 10.2210/pdb1beu/pdb
• Descriptor: TRYPTOPHAN SYNTHASE, INDOLE-3-PROPANOL PHOSPHATE, POTASSIUM ION, ... (6 entities in total)
• Functional Keywords: carbon-oxygen lyase, mutation d60n in a-subunit, indole-3-propanol phosphate in a-subunit, l-serine in b-subunit
• Biological source: Salmonella typhimurium; More
• Total number of polymer chains: 2
• Total formula weight: 72301.39

Authors

Rhee, S.,Mozzarelli, A.,Miles, E.W.,Davies, D.R. (deposition date: 1998-05-18, release date: 1998-08-12, Last modification date: 2024-02-07)

Primary citation

Rhee, S.,Miles, E.W.,Mozzarelli, A.,Davies, D.R.
Cryocrystallography and microspectrophotometry of a mutant (alpha D60N) tryptophan synthase alpha 2 beta 2 complex reveals allosteric roles of alpha Asp60.
Biochemistry, 37:10653-10659, 1998

PubMed Abstract: We have investigated the role of Asp60 of the alpha-subunit in allosteric communication between the tryptophan synthase alpha- and beta-subunits. Crystallographic and microspectrophotometric studies have been carried out on a mutant (alpha D60N) tryptophan synthase alpha 2 beta 2 complex which has no observable alpha-activity, but has substantial beta-activity. Single-crystal polarized absorption spectra indicate that the external aldimine is the predominant L-serine intermediate and that the amount of the intermediate formed is independent of pH, monovalent cations, and allosteric effectors. The three-dimensional structure is reported for this mutant enzyme complexed with indole 3-propanol phosphate bound to the alpha-site and L-serine bound to the beta-site (alpha D60N-IPP-Ser), and this structure is compared with that of the unliganded mutant enzyme (alpha D60N). In the complex, L-serine forms a stable external aldimine with the pyridoxal phosphate coenzyme at the active site of the beta-subunit. The conformation of the unliganded mutant is almost identical to that of the wild type enzyme. However, the structure of the mutant complexed with IPP and serine exhibits ligand-induced conformational changes much smaller than those observed previously for another mutant enzyme in the presence of the same ligands (beta K87T-IPP-Ser) [Rhee, S., Parris, K. D., Hyde, C. C., Ahmed, S. A., Miles, E. W., and Davies, D. R. (1997) Biochemistry 36, 7664-7680]. The alpha D60N-IPP-Ser alpha 2 beta 2 complex does not undergo the following ligand-induced conformational changes: (1) the closure of the alpha-subunit loop 6 (residues 178-191), (2) the movement of the mobile subdomain (residues 93-189) of the beta-subunit, and (3) the rotation of the alpha-subunit relative to the beta-subunit. These observations show that alpha Asp60 plays important roles in the closure of loop 6 and in allosteric communication between the alpha- and beta-subunits.

PubMed: 9692955
DOI: 10.1021/bi980779d

Experimental method

X-RAY DIFFRACTION (1.9 Å)