1kwk

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(New page: 200px<br /><applet load="1kwk" size="450" color="white" frame="true" align="right" spinBox="true" caption="1kwk, resolution 2.20&Aring;" /> '''Crystal structure of...)
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caption="1kwk, resolution 2.20&Aring;" />
caption="1kwk, resolution 2.20&Aring;" />
'''Crystal structure of Thermus thermophilus A4 beta-galactosidase in complex with galactose'''<br />
'''Crystal structure of Thermus thermophilus A4 beta-galactosidase in complex with galactose'''<br />
==Overview==
==Overview==
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The beta-galactosidase from an extreme thermophile, Thermus thermophilus, A4 (A4-beta-Gal), is thermostable and belongs to the glycoside hydrolase, family 42 (GH-42). As the first known structures of a GH-42 enzyme, we, determined the crystal structures of free and galactose-bound A4-beta-Gal, at 1.6A and 2.2A resolution, respectively. A4-beta-Gal forms a, homotrimeric structure resembling a flowerpot. Each monomer has an active, site located inside a large central tunnel. The N-terminal domain of, A4-beta-Gal has a TIM barrel fold, as predicted from hydrophobic cluster, analysis. The putative catalytic residues of A4-beta-Gal (Glu141 and, Glu312) superimpose well with the catalytic residues of Escherichia coli, beta-galactosidase. The environment around the catalytic nucleophile, (Glu312) is similar to that in the case of E.coli beta-galactosidase, but, the recognition mechanism for a substrate is different. Trp182 of the next, subunit of the trimer constitutes a part of the active-site pocket, indicating that the trimeric structure is essential for the enzyme, activity. Structural comparison with other glycoside hydrolases revealed, that many features of the 4/7 superfamily are conserved in the A4-beta-Gal, structure. On the basis of the results of 1H NMR spectroscopy, A4-beta-Gal, was determined to be a "retaining" enzyme. Interestingly, the active site, was similar with those of retaining enzymes, but the overall fold of the, TIM barrel domain was very similar to that of an inverting enzyme, beta-amylase.
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The beta-galactosidase from an extreme thermophile, Thermus thermophilus A4 (A4-beta-Gal), is thermostable and belongs to the glycoside hydrolase family 42 (GH-42). As the first known structures of a GH-42 enzyme, we determined the crystal structures of free and galactose-bound A4-beta-Gal at 1.6A and 2.2A resolution, respectively. A4-beta-Gal forms a homotrimeric structure resembling a flowerpot. Each monomer has an active site located inside a large central tunnel. The N-terminal domain of A4-beta-Gal has a TIM barrel fold, as predicted from hydrophobic cluster analysis. The putative catalytic residues of A4-beta-Gal (Glu141 and Glu312) superimpose well with the catalytic residues of Escherichia coli beta-galactosidase. The environment around the catalytic nucleophile (Glu312) is similar to that in the case of E.coli beta-galactosidase, but the recognition mechanism for a substrate is different. Trp182 of the next subunit of the trimer constitutes a part of the active-site pocket, indicating that the trimeric structure is essential for the enzyme activity. Structural comparison with other glycoside hydrolases revealed that many features of the 4/7 superfamily are conserved in the A4-beta-Gal structure. On the basis of the results of 1H NMR spectroscopy, A4-beta-Gal was determined to be a "retaining" enzyme. Interestingly, the active site was similar with those of retaining enzymes, but the overall fold of the TIM barrel domain was very similar to that of an inverting enzyme, beta-amylase.
==About this Structure==
==About this Structure==
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1KWK is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Thermus_thermophilus Thermus thermophilus] with GAL, CL, ACT, ZN and MPD as [http://en.wikipedia.org/wiki/ligands ligands]. Active as [http://en.wikipedia.org/wiki/Beta-galactosidase Beta-galactosidase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=3.2.1.23 3.2.1.23] Full crystallographic information is available from [http://ispc.weizmann.ac.il/oca-bin/ocashort?id=1KWK OCA].
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1KWK is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Thermus_thermophilus Thermus thermophilus] with <scene name='pdbligand=GAL:'>GAL</scene>, <scene name='pdbligand=CL:'>CL</scene>, <scene name='pdbligand=ACT:'>ACT</scene>, <scene name='pdbligand=ZN:'>ZN</scene> and <scene name='pdbligand=MPD:'>MPD</scene> as [http://en.wikipedia.org/wiki/ligands ligands]. Active as [http://en.wikipedia.org/wiki/Beta-galactosidase Beta-galactosidase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=3.2.1.23 3.2.1.23] Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1KWK OCA].
==Reference==
==Reference==
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[[Category: trimer]]
[[Category: trimer]]
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''Page seeded by [http://ispc.weizmann.ac.il/oca OCA ] on Sun Nov 25 02:05:18 2007''
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''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 13:38:43 2008''

Revision as of 11:38, 21 February 2008

Image:1kwk.jpg

1kwk, resolution 2.20Å

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Crystal structure of Thermus thermophilus A4 beta-galactosidase in complex with galactose

Overview

The beta-galactosidase from an extreme thermophile, Thermus thermophilus A4 (A4-beta-Gal), is thermostable and belongs to the glycoside hydrolase family 42 (GH-42). As the first known structures of a GH-42 enzyme, we determined the crystal structures of free and galactose-bound A4-beta-Gal at 1.6A and 2.2A resolution, respectively. A4-beta-Gal forms a homotrimeric structure resembling a flowerpot. Each monomer has an active site located inside a large central tunnel. The N-terminal domain of A4-beta-Gal has a TIM barrel fold, as predicted from hydrophobic cluster analysis. The putative catalytic residues of A4-beta-Gal (Glu141 and Glu312) superimpose well with the catalytic residues of Escherichia coli beta-galactosidase. The environment around the catalytic nucleophile (Glu312) is similar to that in the case of E.coli beta-galactosidase, but the recognition mechanism for a substrate is different. Trp182 of the next subunit of the trimer constitutes a part of the active-site pocket, indicating that the trimeric structure is essential for the enzyme activity. Structural comparison with other glycoside hydrolases revealed that many features of the 4/7 superfamily are conserved in the A4-beta-Gal structure. On the basis of the results of 1H NMR spectroscopy, A4-beta-Gal was determined to be a "retaining" enzyme. Interestingly, the active site was similar with those of retaining enzymes, but the overall fold of the TIM barrel domain was very similar to that of an inverting enzyme, beta-amylase.

About this Structure

1KWK is a Single protein structure of sequence from Thermus thermophilus with , , , and as ligands. Active as Beta-galactosidase, with EC number 3.2.1.23 Full crystallographic information is available from OCA.

Reference

Trimeric crystal structure of the glycoside hydrolase family 42 beta-galactosidase from Thermus thermophilus A4 and the structure of its complex with galactose., Hidaka M, Fushinobu S, Ohtsu N, Motoshima H, Matsuzawa H, Shoun H, Wakagi T, J Mol Biol. 2002 Sep 6;322(1):79-91. PMID:12215416

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