1moq: Difference between revisions

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ISOMERASE DOMAIN OF GLUCOSAMINE 6-PHOSPHATE SYNTHASE COMPLEXED WITH GLUCOSAMINE 6-PHOSPHATE

OverviewOverview

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 StructureAbout this Structure

1MOQ is a Single protein structure of sequence from Escherichia coli with , , , and as ligands. Active as Glutamine--fructose-6-phosphate transaminase (isomerizing), with EC number 2.6.1.16 Full crystallographic information is available from OCA.

ReferenceReference

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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-[[Image:1moq.jpg|left|200px]]<br /><applet load="1moq" size="450" color="white" frame="true" align="right" spinBox="true"
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 caption="1moq, resolution 1.57&Aring;" />
 '''ISOMERASE DOMAIN OF GLUCOSAMINE 6-PHOSPHATE SYNTHASE COMPLEXED WITH GLUCOSAMINE 6-PHOSPHATE'''<br />
 ==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.
+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==
-MOQ 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 GLP, SO4, NA, MES and MRD as [http://en.wikipedia.org/wiki/ligands ligands]. 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://ispc.weizmann.ac.il/oca-bin/ocashort?id=1MOQ OCA].
+MOQ 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=GLP:'>GLP</scene>, <scene name='pdbligand=SO4:'>SO4</scene>, <scene name='pdbligand=NA:'>NA</scene>, <scene name='pdbligand=MES:'>MES</scene> and <scene name='pdbligand=MRD:'>MRD</scene> as [http://en.wikipedia.org/wiki/ligands ligands]. 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=1MOQ OCA].
 ==Reference==
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 [[Category: glutamine amidotransferase]]
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