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| - | [[Image:1beu.gif|left|200px]] | + | {{Seed}} |
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| | {{STRUCTURE_1beu| PDB=1beu | SCENE= }} | | {{STRUCTURE_1beu| PDB=1beu | SCENE= }} |
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| - | '''TRP SYNTHASE (D60N-IPP-SER) WITH K+'''
| + | ===TRP SYNTHASE (D60N-IPP-SER) WITH K+=== |
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| - | ==Overview==
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| - | 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.
| + | The line below this paragraph, {{ABSTRACT_PUBMED_9692955}}, adds the Publication Abstract to the page |
| | + | (as it appears on PubMed at http://www.pubmed.gov), where 9692955 is the PubMed ID number. |
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| | + | {{ABSTRACT_PUBMED_9692955}} |
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| | ==About this Structure== | | ==About this Structure== |
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| | [[Category: L-serine in b-subunit]] | | [[Category: L-serine in b-subunit]] |
| | [[Category: Mutation d60n in a-subunit]] | | [[Category: Mutation d60n in a-subunit]] |
| - | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Fri May 2 11:25:33 2008'' | + | |
| | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Mon Jun 30 19:00:07 2008'' |
Revision as of 16:00, 30 June 2008
Template:STRUCTURE 1beu
TRP SYNTHASE (D60N-IPP-SER) WITH K+
Template:ABSTRACT PUBMED 9692955
About this Structure
1BEU is a Protein complex structure of sequences from Salmonella typhimurium. 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
Page seeded by OCA on Mon Jun 30 19:00:07 2008
