1beu
From Proteopedia
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==Overview== | ==Overview== | ||
| - | 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 ... [ | + | 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. |
==About this Structure== | ==About this Structure== | ||
| - | 1BEU is a | + | 1BEU is a [http://en.wikipedia.org/wiki/Protein_complex Protein complex] structure of sequences from [http://en.wikipedia.org/wiki/Salmonella_typhimurium Salmonella typhimurium] with K, IPL and PLS as [http://en.wikipedia.org/wiki/ligands ligands]. Active as [http://en.wikipedia.org/wiki/Tryptophan_synthase Tryptophan synthase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=4.2.1.20 4.2.1.20] Structure known Active Sites: NUA and NUB. Full crystallographic information is available from [http://ispc.weizmann.ac.il/oca-bin/ocashort?id=1BEU OCA]. |
==Reference== | ==Reference== | ||
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[[Category: mutation d60n in a-subunit]] | [[Category: mutation d60n in a-subunit]] | ||
| - | ''Page seeded by [http://ispc.weizmann.ac.il/oca OCA ] on | + | ''Page seeded by [http://ispc.weizmann.ac.il/oca OCA ] on Mon Nov 5 14:54:10 2007'' |
Revision as of 12:48, 5 November 2007
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TRP SYNTHASE (D60N-IPP-SER) WITH K+
Overview
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.
About this Structure
1BEU is a Protein complex structure of sequences from Salmonella typhimurium with K, IPL and PLS as ligands. Active as Tryptophan synthase, with EC number 4.2.1.20 Structure known Active Sites: NUA and NUB. Full crystallographic information is available from OCA.
Reference
Cryocrystallography and microspectrophotometry of a mutant (alpha D60N) tryptophan synthase alpha 2 beta 2 complex reveals allosteric roles of alpha Asp60., Rhee S, Miles EW, Mozzarelli A, Davies DR, Biochemistry. 1998 Jul 28;37(30):10653-9. PMID:9692955
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