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1pzt

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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'''
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===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.
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(as it appears on PubMed at http://www.pubmed.gov), where 12927542 is the PubMed ID number.
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{{ABSTRACT_PUBMED_12927542}}
==About this Structure==
==About this Structure==
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[[Category: Protease digestion]]
[[Category: Protease digestion]]
[[Category: Substrate binding]]
[[Category: Substrate binding]]
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''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Sat May 3 05:41:34 2008''
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''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

Image:1pzt.png

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

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