1mor
From Proteopedia
(New page: 200px<br /><applet load="1mor" size="450" color="white" frame="true" align="right" spinBox="true" caption="1mor, resolution 1.90Å" /> '''ISOMERASE DOMAIN OF ...) |
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| - | [[Image:1mor.gif|left|200px]]<br /><applet load="1mor" size=" | + | [[Image:1mor.gif|left|200px]]<br /><applet load="1mor" size="350" color="white" frame="true" align="right" spinBox="true" |
caption="1mor, resolution 1.90Å" /> | caption="1mor, resolution 1.90Å" /> | ||
'''ISOMERASE DOMAIN OF GLUCOSAMINE 6-PHOSPHATE SYNTHASE COMPLEXED WITH GLUCOSE 6-PHOSPHATE'''<br /> | '''ISOMERASE DOMAIN OF GLUCOSAMINE 6-PHOSPHATE SYNTHASE COMPLEXED WITH GLUCOSE 6-PHOSPHATE'''<br /> | ||
==Overview== | ==Overview== | ||
| - | BACKGROUND: Glucosamine 6-phosphate synthase (GlmS) catalyses the first | + | BACKGROUND: Glucosamine 6-phosphate synthase (GlmS) catalyses the first step in hexosamine metabolism, converting fructose-6P (6 phosphate) into glucosamine-6P using glutamine as a nitrogen source. GlmS is a bienzyme complex consisting of two domains that catalyse glutamine hydrolysis and sugar-phosphate isomerisation, respectively. Knowledge of the three-dimensional structure of GlmS is essential for understanding the general principles of catalysis by ketol isomerases and the mechanism of nitrogen transfer in glutamine amidotransferases. RESULTS: The crystal structure of the isomerase domain of the Escherichia coli GlmS with the reaction product, glucosamine-6P, has been determined at 1.57 A resolution. It is comprised of two topologically identical subdomains, each of which is dominated by a nucleotide-binding motif of a flavodoxin type. The catalytic site is assembled by dimerisation of the protein. CONCLUSIONS: The isomerase active site of GlmS seems to be the result of evolution through gene duplication and subsequent dimerisation. Isomerisation of fructose-6P is likely to involve the formation of a Schiff base with Lys603 of the enzyme, the ring-opening step catalysed by His504, and the proton transfer from C1 to C2 of the substrate effected by Glu488. The highly conserved C-terminal fragment of the chain may play a key role in substrate binding, catalysis and communication with the glutaminase domain. The corresponding sequence pattern DXPXXLAK[SC]VT (in single-letter amino-acid code, where X is any amino acid and letters in brackets indicate that either serine or cysteine may take this position) may be considered as a fingerprint of GlmS. |
==About this Structure== | ==About this Structure== | ||
| - | 1MOR is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Escherichia_coli Escherichia coli] with G6P as [http://en.wikipedia.org/wiki/ligand ligand]. Active as [http://en.wikipedia.org/wiki/Glutamine--fructose-6-phosphate_transaminase_(isomerizing) Glutamine--fructose-6-phosphate transaminase (isomerizing)], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=2.6.1.16 2.6.1.16] Full crystallographic information is available from [http:// | + | 1MOR is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Escherichia_coli Escherichia coli] with <scene name='pdbligand=G6P:'>G6P</scene> as [http://en.wikipedia.org/wiki/ligand ligand]. Active as [http://en.wikipedia.org/wiki/Glutamine--fructose-6-phosphate_transaminase_(isomerizing) Glutamine--fructose-6-phosphate transaminase (isomerizing)], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=2.6.1.16 2.6.1.16] Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1MOR OCA]. |
==Reference== | ==Reference== | ||
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[[Category: glutamine amidotransferase]] | [[Category: glutamine amidotransferase]] | ||
| - | ''Page seeded by [http:// | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 13:57:24 2008'' |
Revision as of 11:57, 21 February 2008
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ISOMERASE DOMAIN OF GLUCOSAMINE 6-PHOSPHATE SYNTHASE COMPLEXED WITH GLUCOSE 6-PHOSPHATE
Overview
BACKGROUND: Glucosamine 6-phosphate synthase (GlmS) catalyses the first step in hexosamine metabolism, converting fructose-6P (6 phosphate) into glucosamine-6P using glutamine as a nitrogen source. GlmS is a bienzyme complex consisting of two domains that catalyse glutamine hydrolysis and sugar-phosphate isomerisation, respectively. Knowledge of the three-dimensional structure of GlmS is essential for understanding the general principles of catalysis by ketol isomerases and the mechanism of nitrogen transfer in glutamine amidotransferases. RESULTS: The crystal structure of the isomerase domain of the Escherichia coli GlmS with the reaction product, glucosamine-6P, has been determined at 1.57 A resolution. It is comprised of two topologically identical subdomains, each of which is dominated by a nucleotide-binding motif of a flavodoxin type. The catalytic site is assembled by dimerisation of the protein. CONCLUSIONS: The isomerase active site of GlmS seems to be the result of evolution through gene duplication and subsequent dimerisation. Isomerisation of fructose-6P is likely to involve the formation of a Schiff base with Lys603 of the enzyme, the ring-opening step catalysed by His504, and the proton transfer from C1 to C2 of the substrate effected by Glu488. The highly conserved C-terminal fragment of the chain may play a key role in substrate binding, catalysis and communication with the glutaminase domain. The corresponding sequence pattern DXPXXLAK[SC]VT (in single-letter amino-acid code, where X is any amino acid and letters in brackets indicate that either serine or cysteine may take this position) may be considered as a fingerprint of GlmS.
About this Structure
1MOR is a Single protein structure of sequence from Escherichia coli with as ligand. Active as Glutamine--fructose-6-phosphate transaminase (isomerizing), with EC number 2.6.1.16 Full crystallographic information is available from OCA.
Reference
Involvement of the C terminus in intramolecular nitrogen channeling in glucosamine 6-phosphate synthase: evidence from a 1.6 A crystal structure of the isomerase domain., Teplyakov A, Obmolova G, Badet-Denisot MA, Badet B, Polikarpov I, Structure. 1998 Aug 15;6(8):1047-55. PMID:9739095
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