From Proteopedia
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| - | [[Image:1pzt.gif|left|200px]] | + | {{Seed}} |
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| | {{STRUCTURE_1pzt| PDB=1pzt | SCENE= }} | | {{STRUCTURE_1pzt| PDB=1pzt | SCENE= }} |
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| - | '''CRYSTAL STRUCTURE OF W314A-BETA-1,4-GALACTOSYLTRANSFERASE (B4GAL-T1) CATALYTIC DOMAIN WITHOUT SUBSTRATE'''
| + | ===CRYSTAL STRUCTURE OF W314A-BETA-1,4-GALACTOSYLTRANSFERASE (B4GAL-T1) CATALYTIC DOMAIN WITHOUT SUBSTRATE=== |
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| - | ==Overview==
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| - | beta1,4-Galactosyltransferase-I (beta4Gal-T1) undergoes critical conformational changes upon substrate binding from an open conformation (conf-I) to the closed conformation (conf-II). This change involves two flexible loops: the small (residues 313-316) and the long loop (residues 345-365). Upon substrate binding, Trp314 in the small flexible loop moves towards the catalytic pocket and interacts with the donor and the acceptor substrates. For a better understanding of the role played by Trp314 in the conformational changes of beta4Gal-T1, we mutated it to Ala and carried out substrate-binding, proteolytic and crystallographic studies. The W314A mutation reduces the enzymatic activity, binding to substrates and to the modifier protein, alpha-lactalbumin (LA), by over 99%. The limited proteolysis with Glu-C or Lys-C proteases shows differences in the rate of cleavage of the long loop of the wild-type and mutant W314A, indicating conformational differences in the region between the two proteins. Without substrate, the mutant crystallizes in a conformation (conf-I') (1.9A resolution crystal structure), that is not identical with, but close to an open conformation (conf-I), whereas its complex with the substrates and alpha-lactalbumin, crystallizes in a conformation (2.3A resolution crystal structure) that is identical with the closed conformation (conf-II). This study shows the crucial role Trp314 plays in the conformational state of the long loop, in the binding of substrates and in the catalytic mechanism of the enzyme.
| + | The line below this paragraph, {{ABSTRACT_PUBMED_12927542}}, adds the Publication Abstract to the page |
| | + | (as it appears on PubMed at http://www.pubmed.gov), where 12927542 is the PubMed ID number. |
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| | + | {{ABSTRACT_PUBMED_12927542}} |
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| | ==About this Structure== | | ==About this Structure== |
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| | [[Category: Protease digestion]] | | [[Category: Protease digestion]] |
| | [[Category: Substrate binding]] | | [[Category: Substrate binding]] |
| - | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Sat May 3 05:41:34 2008'' | + | |
| | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Sun Jul 27 19:03:58 2008'' |
Revision as of 16:04, 27 July 2008
Template:STRUCTURE 1pzt
CRYSTAL STRUCTURE OF W314A-BETA-1,4-GALACTOSYLTRANSFERASE (B4GAL-T1) CATALYTIC DOMAIN WITHOUT SUBSTRATE
Template:ABSTRACT PUBMED 12927542
About this Structure
1PZT is a Single protein structure of sequence from Bos taurus. Full crystallographic information is available from OCA.
Reference
The role of tryptophan 314 in the conformational changes of beta1,4-galactosyltransferase-I., Ramasamy V, Ramakrishnan B, Boeggeman E, Qasba PK, J Mol Biol. 2003 Aug 29;331(5):1065-76. PMID:12927542
Page seeded by OCA on Sun Jul 27 19:03:58 2008
