Domain Annotation: SCOP2 Classification SCOP2 Database Homepage

ChainsTypeFamily Name Domain Identifier Family IdentifierProvenance Source (Version)
BSCOP2B SuperfamilySIS domain/Ribosomal protein S2-like 8052796 3001397 SCOP2B (2022-06-29)
BSCOP2B SuperfamilySIS domain/Ribosomal protein S2-like 8032993 3001397 SCOP2B (2022-06-29)
BSCOP2B SuperfamilyClass II glutamine amidotransferases 8041848 3000131 SCOP2B (2022-06-29)
CSCOP2B SuperfamilyClass II glutamine amidotransferases 8041848 3000131 SCOP2B (2022-06-29)
CSCOP2B SuperfamilySIS domain/Ribosomal protein S2-like 8032993 3001397 SCOP2B (2022-06-29)
CSCOP2B SuperfamilySIS domain/Ribosomal protein S2-like 8052796 3001397 SCOP2B (2022-06-29)
ASCOP2B SuperfamilySIS domain/Ribosomal protein S2-like 8052796 3001397 SCOP2B (2022-06-29)
ASCOP2B SuperfamilyClass II glutamine amidotransferases 8041848 3000131 SCOP2B (2022-06-29)
ASCOP2B SuperfamilySIS domain/Ribosomal protein S2-like 8032993 3001397 SCOP2B (2022-06-29)

Domain Annotation: ECOD Classification ECOD Database Homepage

ChainsFamily NameDomain Identifier ArchitecturePossible HomologyHomologyTopologyFamilyProvenance Source (Version)
BGATase_2_1ste1jxaB5 A: a+b four layersX: Ntn/PP2CH: NtnT: Class II glutamine amidotransferasesF: GATase_2_1stECOD (1.6)
BSIS_3e1jxaB3 A: a/b three-layered sandwichesX: Flavodoxin-likeH: Ribosomal protein S2/SIS domain (From Topology)T: Ribosomal protein S2/SIS domainF: SIS_3ECOD (1.6)
CGATase_2_1ste1jxaC5 A: a+b four layersX: Ntn/PP2CH: NtnT: Class II glutamine amidotransferasesF: GATase_2_1stECOD (1.6)
CSIS_3e1jxaC3 A: a/b three-layered sandwichesX: Flavodoxin-likeH: Ribosomal protein S2/SIS domain (From Topology)T: Ribosomal protein S2/SIS domainF: SIS_3ECOD (1.6)
AGATase_2_1ste1jxaA5 A: a+b four layersX: Ntn/PP2CH: NtnT: Class II glutamine amidotransferasesF: GATase_2_1stECOD (1.6)
ASIS_3e1jxaA3 A: a/b three-layered sandwichesX: Flavodoxin-likeH: Ribosomal protein S2/SIS domain (From Topology)T: Ribosomal protein S2/SIS domainF: SIS_3ECOD (1.6)

Domain Annotation: CATH CATH Database Homepage

Protein Family Annotation Pfam Database Homepage

ChainsAccessionNameDescriptionCommentsSource
A, B, C
PF01380SIS domain (SIS)SIS domainSIS (Sugar ISomerase) domains are found in many phosphosugar isomerases and phosphosugar binding proteins. SIS domains are also found in proteins that regulate the expression of genes involved in synthesis of phosphosugars. Presumably the SIS domain ...SIS (Sugar ISomerase) domains are found in many phosphosugar isomerases and phosphosugar binding proteins. SIS domains are also found in proteins that regulate the expression of genes involved in synthesis of phosphosugars. Presumably the SIS domains bind to the end-product of the pathway.
Domain
A, B, C
PF13522Glutamine amidotransferase domain (GATase_6)Glutamine amidotransferase domainThis domain is a class-II glutamine amidotransferase domain found in a variety of enzymes, such as asparagine synthetase and glutamine--fructose-6-phosphate transaminase.Domain

Gene Ontology: Gene Product Annotation Gene Ontology Database Homepage

ChainsPolymerMolecular FunctionBiological ProcessCellular Component
A, B, C
glucosamine 6-phosphate synthase

Structure Motif Annotation: Mechanism and Catalytic Site Atlas M-CSA Database Homepage

ChainsEnzyme NameDescriptionCatalytic Residues
glutamine-fructose-6-phosphate transaminase (isomerizing)  M-CSA #82

Glucosamine-fructose-6-phosphate aminotransferase (isomerizing) also known as Glucosamine-6-phosphate synthase (GlmS), catalyses the first reaction in hexamine biosynthesis. It belongs to an F-type group of glutamine-dependent amidotransferase family of enzymes, which utilise the glutamine amide nitrogen in the biosynthesis of phosphoribosylamine, glutamate or asparagine.

The hexosamine biosynthetic pathway starts from D fructose-6-phosphate (Fru6P)2 which is produced from glucose via the glycolysis pathway. The Fru6P is converted into D -glucosamine-6-phosphate (GlcN6P) by the rate-limiting enzyme glucosamine-6-phosphate synthase (GlcN6P synthase). This is the sole biosynthetic route to GlcN6P known to date.

The reaction is practically irreversible and the reaction takes place over two structural domains, an N-terminal glutaminase domain, which hydrolyses glutamine to glutamate and ammonia (residues 1-240), and a C-terminal isomerase domain (residues 241-608), which catalyses the ketose-aldose isomerisation and utilises the nitrogen for synthesis of GlcN-6P.

The isomerase domain is responsible for two activities of GlmS, the conversion of Fru-6P into GlcN-6P in the presence of glutamine (the synthase activity), and the isomerisation of Fru-6P into Glc-6P (the phosphoglucose isomerase - like activity) in the absence of glutamine.

The product of the reaction with fructose 6-phosphate, glucosamine 6-phosphate, undergoes transformation leading towards formation of uridine diphospho-N-acetylglucosamine - which is a precursor to all amino sugar-containing macromolecules. Much interest has been shown in this enzyme that is believed to have important implications in antibacterial/antifungal therapy and diabetes treatment.

Defined by 10 residues: CYS:A-1ARG:A-26TRP:A-74ASN:A-98GLY:A-99GLU:A-481LYS:A-485GLU:A-488HIS:A_2-504LYS:A-603
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