Ribose 5-phosphate isomerase () forms a homodimer and catalyses the interconversion of D-ribose 5-phosphate and D-ribulose 5-phosphate in the non-oxidative branch of the pentose phosphate pathway. This reaction permits the synthesis of ribose from other sugars, as well as the recycling of sugars from nucleotide breakdown. Two unrelated enzymes can catalyse this reaction: RpiA (found in most organisms) and RpiB (found in some bacteria and eukaryotes). RpiB is also involved in metabolism of the rare sugar, allose, in addition to ribose sugars. The structures of RpiA and RpiB are distinct, RpiB having a Rossmann-type alpha/beta/alpha sandwich topology [].This entry represents the RpiB enzyme. It also includes D-erythrulose-4-phosphate isomerase from Pectobacterium atrosepticum [].
This entry is composed of multiple transferases, mainly ribose-5-phosphate isomerase A (RpiA), glucosamine-6-phosphate deaminase (NagB) and 6-phosphogluconolactonase (6PGL). RpiA and 6PGL are involved in the pentose phosphate pathway while NagB is involved in the last step of the N-acetylneuraminate degradation pathway. These enzymes share a common core α/β structure [].
Ribose 5-phosphate isomerase, also known as phosphoriboisomerase, catalyses the reversible conversion of D-ribose 5-phosphate to D-ribulose 5-phosphate, the first step in the non-oxidative branch of the pentose phosphate pathway []. This reaction enables ribose to be synthesized from sugars, as well as the recycling of sugars during the degradation of nucleotides. There are two unrelated types of ribose 5-phosphate isomerases: type A (RpiA) is the most common and is found in most organisms, while type B (RpiB) is restricted to specific eukaryotic and prokaryotic species. Escherichia coli produces both RpiA and RpiB (also known as AlsB), although RpiA accounts for 99% of total RPI enzymes []. This entry represents type A (RpiA) enzymes found in eukaryotes (plants, Metazoa and fungi), bacteria and archaea.
Ribose 5-phosphate isomerase, also known as phosphoriboisomerase, catalyses the reversible conversion of D-ribose 5-phosphate to D-ribulose 5-phosphate, the first step in the non-oxidative branch of the pentose phosphate pathway []. This reaction enables ribose to be synthesized from sugars, as well as the recycling of sugars during the degradation of nucleotides. There are two unrelated types of ribose 5-phosphate isomerases: type A (RpiA) is the most common and is found in most organisms, while type B (RpiB) is restricted to specific eukaryotic and prokaryotic species. Escherichia coli produces both RpiA and RpiB (also known as AlsB), although RpiA accounts for 99% of total RPI enzymes []. This entry represents a subgroup of type A ribose-5-phosphate isomerase that is found in bacteria, archaea and eukaryotes (plants and Metazoa), but excluding those found in fungi.
This entry represents the sugar isomerase enzymes ribose 5-phosphate isomerase B (RpiB), galactose isomerase subunit A (LacA) and galactose isomerase subunit B (LacB). Galactose-6-phosphate isomerase () is a heteromultimeric protein consisting of subunits LacA and LacB, and catalyses the conversion of D-galactose 6-phosphate to D-tagatose and 6-phosphate in the tagatose 6-phosphate pathway of lactose catabolism []. Galactose-6-phosphate isomerase is induced by galactose or lactose.Ribose 5-phosphate isomerase () forms a homodimer and catalyses the interconversion of D-ribose 5-phosphate and D-ribulose 5-phosphate in the non-oxidative branch of the pentose phosphate pathway. This reaction permits the synthesis of ribose from other sugars, as well as the recycling of sugars from nucleotide breakdown. Two unrelated enzymes can catalyse this reaction: RpiA (found in most organisms) and RpiB (found in some bacteria and eukaryotes). RpiB is also involved in metabolism of the rare sugar, allose, in addition to ribose sugars. The structures of RpiA and RpiB are distinct, RpiB having a Rossmann-type alpha/beta/alpha sandwich topology [].
This entry represents the sugar isomerase enzymes ribose 5-phosphate isomerase B (RpiB), galactose isomerase subunit A (LacA) and galactose isomerase subunit B (LacB). Galactose-6-phosphate isomerase () is a heteromultimeric protein consisting of subunits LacA and LacB, and catalyses the conversion of D-galactose 6-phosphate to D-tagatose and 6-phosphate in the tagatose 6-phosphate pathway of lactose catabolism []. Galactose-6-phosphate isomerase is induced by galactose or lactose.Ribose 5-phosphate isomerase () forms a homodimer and catalyses the interconversion of D-ribose 5-phosphate and D-ribulose 5-phosphate in the non-oxidative branch of the pentose phosphate pathway. This reaction permits the synthesis of ribose from other sugars, as well as the recycling of sugars from nucleotide breakdown. Two unrelated enzymes can catalyse this reaction: RpiA (found in most organisms) and RpiB (found in some bacteria and eukaryotes). RpiB is also involved in metabolism of the rare sugar, allose, in addition to ribose sugars. The structures of RpiA and RpiB are distinct, RpiB having a Rossmann-type alpha/beta/alpha sandwich topology [].
RpiR contains a SIS (Sugar ISomerase) domain, which is found in many phosphosugar isomerases and phosphosugar binding proteins. In E. coli, RpiR negatively regulates the expression of rpiB gene. Both rpiB and rpiA are ribose phosphate isomerases that catalyze the reversible reactions of ribose 5-phosphate into ribulose 5-phosphate [].This domain is also found in other members of the RpiR family of transcriptional regulators, such as MurR []and in uncharacterised proteins of the UPF0309 family.
This family is a member of the RpiB/LacA/LacB family. It includes ribose 5-phosphate isomerases and D-erythrulose-4-phosphate isomerases []. The only candidates for ribose 5-phosphate isomerase in the Actinobacteria are members of this family [, ].Ribose 5-phosphate isomerase () forms a homodimer and catalyses the interconversion of D-ribose 5-phosphate and D-ribulose 5-phosphate in the non-oxidative branch of the pentose phosphate pathway. This reaction permits the synthesis of ribose from other sugars, as well as the recycling of sugars from nucleotide breakdown. Two unrelated enzymes can catalyse this reaction: RpiA (found in most organisms) and RpiB (found in some bacteria and eukaryotes).
