1db3
From Proteopedia
(New page: 200px<br /><applet load="1db3" size="450" color="white" frame="true" align="right" spinBox="true" caption="1db3, resolution 2.3Å" /> '''E.COLI GDP-MANNOSE 4,...) |
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| - | [[Image:1db3.gif|left|200px]]<br /><applet load="1db3" size=" | + | [[Image:1db3.gif|left|200px]]<br /><applet load="1db3" size="350" color="white" frame="true" align="right" spinBox="true" |
caption="1db3, resolution 2.3Å" /> | caption="1db3, resolution 2.3Å" /> | ||
'''E.COLI GDP-MANNOSE 4,6-DEHYDRATASE'''<br /> | '''E.COLI GDP-MANNOSE 4,6-DEHYDRATASE'''<br /> | ||
==Overview== | ==Overview== | ||
| - | Background: GDP-mannose 4,6 dehydratase (GMD) catalyzes the conversion of | + | Background: GDP-mannose 4,6 dehydratase (GMD) catalyzes the conversion of GDP-(D)-mannose to GDP-4-keto, 6-deoxy-(D)-mannose. This is the first and regulatory step in the de novo biosynthesis of GDP-(L)-fucose. Fucose forms part of a number of glycoconjugates, including the ABO blood groups and the selectin ligand sialyl Lewis X. Defects in GDP-fucose metabolism have been linked to leukocyte adhesion deficiency type II (LADII). Results: The structure of the GDP-mannose 4,6 dehydratase apo enzyme has been determined and refined using data to 2.3 A resolution. GMD is a homodimeric protein with each monomer composed of two domains. The larger N-terminal domain binds the NADP(H) cofactor in a classical Rossmann fold and the C-terminal domain harbors the sugar-nucleotide binding site. We have determined the GMD dissociation constants for NADP, NADPH and GDP-mannose. Each GMD monomer binds one cofactor and one substrate molecule, suggesting that both subunits are catalytically competent. GDP-fucose acts as a competitive inhibitor, suggesting that it binds to the same site as GDP-mannose, providing a mechanism for the feedback inhibition of fucose biosynthesis. Conclusions: The X-ray structure of GMD reveals that it is a member of the short-chain dehydrogenase/reductase (SDR) family of proteins. We have modeled the binding of NADP and GDP-mannose to the enzyme and mutated four of the active-site residues to determine their function. The combined modeling and mutagenesis data suggests that at position 133 threonine substitutes serine as part of the serine-tyrosine-lysine catalytic triad common to the SDR family and Glu 135 functions as an active-site base. |
==About this Structure== | ==About this Structure== | ||
| - | 1DB3 is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Escherichia_coli Escherichia coli]. Active as [http://en.wikipedia.org/wiki/GDP-mannose_4,6-dehydratase GDP-mannose 4,6-dehydratase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=4.2.1.47 4.2.1.47] Full crystallographic information is available from [http:// | + | 1DB3 is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Escherichia_coli Escherichia coli]. Active as [http://en.wikipedia.org/wiki/GDP-mannose_4,6-dehydratase GDP-mannose 4,6-dehydratase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=4.2.1.47 4.2.1.47] Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1DB3 OCA]. |
==Reference== | ==Reference== | ||
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[[Category: Single protein]] | [[Category: Single protein]] | ||
[[Category: Menon, S.]] | [[Category: Menon, S.]] | ||
| - | [[Category: Somers, W | + | [[Category: Somers, W S.]] |
| - | [[Category: Somoza, J | + | [[Category: Somoza, J R.]] |
| - | [[Category: Sullivan, F | + | [[Category: Sullivan, F X.]] |
[[Category: dehydratase]] | [[Category: dehydratase]] | ||
[[Category: gdp-fucose]] | [[Category: gdp-fucose]] | ||
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[[Category: nadp]] | [[Category: nadp]] | ||
| - | ''Page seeded by [http:// | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 12:14:48 2008'' |
Revision as of 10:14, 21 February 2008
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E.COLI GDP-MANNOSE 4,6-DEHYDRATASE
Overview
Background: GDP-mannose 4,6 dehydratase (GMD) catalyzes the conversion of GDP-(D)-mannose to GDP-4-keto, 6-deoxy-(D)-mannose. This is the first and regulatory step in the de novo biosynthesis of GDP-(L)-fucose. Fucose forms part of a number of glycoconjugates, including the ABO blood groups and the selectin ligand sialyl Lewis X. Defects in GDP-fucose metabolism have been linked to leukocyte adhesion deficiency type II (LADII). Results: The structure of the GDP-mannose 4,6 dehydratase apo enzyme has been determined and refined using data to 2.3 A resolution. GMD is a homodimeric protein with each monomer composed of two domains. The larger N-terminal domain binds the NADP(H) cofactor in a classical Rossmann fold and the C-terminal domain harbors the sugar-nucleotide binding site. We have determined the GMD dissociation constants for NADP, NADPH and GDP-mannose. Each GMD monomer binds one cofactor and one substrate molecule, suggesting that both subunits are catalytically competent. GDP-fucose acts as a competitive inhibitor, suggesting that it binds to the same site as GDP-mannose, providing a mechanism for the feedback inhibition of fucose biosynthesis. Conclusions: The X-ray structure of GMD reveals that it is a member of the short-chain dehydrogenase/reductase (SDR) family of proteins. We have modeled the binding of NADP and GDP-mannose to the enzyme and mutated four of the active-site residues to determine their function. The combined modeling and mutagenesis data suggests that at position 133 threonine substitutes serine as part of the serine-tyrosine-lysine catalytic triad common to the SDR family and Glu 135 functions as an active-site base.
About this Structure
1DB3 is a Single protein structure of sequence from Escherichia coli. Active as GDP-mannose 4,6-dehydratase, with EC number 4.2.1.47 Full crystallographic information is available from OCA.
Reference
Structural and kinetic analysis of Escherichia coli GDP-mannose 4,6 dehydratase provides insights into the enzyme's catalytic mechanism and regulation by GDP-fucose., Somoza JR, Menon S, Schmidt H, Joseph-McCarthy D, Dessen A, Stahl ML, Somers WS, Sullivan FX, Structure. 2000 Feb 15;8(2):123-35. PMID:10673432
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