PTS-GFL superfamily

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The phosphotransferases system (PTS-GFL) superfamily is a superfamily of phosphotransferase enzymes that facilitate the transport of glucose, glucitol (G), fructose (F) and lactose (L). Classification has been established through phylogenic analysis and bioinformatics. [1] [2]

A protein superfamily is the largest grouping (clade) of proteins for which common ancestry can be inferred. Usually this common ancestry is inferred from structural alignment and mechanistic similarity, even if no sequence similarity is evident. Sequence homology can then be deduced even if not apparent. Superfamilies typically contain several protein families which show sequence similarity within each family. The term protein clan is commonly used for protease and glycosyl hydrolases superfamilies based on the MEROPS and CAZy classification systems.

Phosphotransferases are a category of enzymes that catalyze phosphorylation reactions. The general form of the reactions they catalyze is:

Fructose A simple ketonic monosaccharide found in many plants

Fructose, or fruit sugar, is a simple ketonic monosaccharide found in many plants, where it is often bonded to glucose to form the disaccharide sucrose. It is one of the three dietary monosaccharides, along with glucose and galactose, that are absorbed directly into blood during digestion. Fructose was discovered by French chemist Augustin-Pierre Dubrunfaut in 1847. The name "fructose" was coined in 1857 by the English chemist William Allen Miller. Pure, dry fructose is a sweet, white, odorless, crystalline solid, and is the most water-soluble of all the sugars. Fructose is found in honey, tree and vine fruits, flowers, berries, and most root vegetables.

Contents

The bacterial phosphoenolpyruvate:sugar phosphotransferase system (PTS) transports and phosphorylates its sugar substrates in a single energy-coupled step. This transport process is dependent on several cytoplasmic phosphoryl transfer proteins - Enzyme I (I), HPr, Enzyme IIA (IIA), and Enzyme IIB (IIB)) as well as the integral membrane sugar permease (IIC). The PTS Enzyme II complexes are derived from independently evolving 4 PTS Enzyme II complex superfamilies, that include the (1) Glucose (Glc),(2) Mannose (Man), (3) Ascorbate-Galactitol (Asc-Gat) and (4) Dihydroxyacetone (Dha) superfamilies.

The four families that make up the PTS-GFL superfamily include:

The PTS Fructose-Mannitol (Fru) Family is a large and complex family that is part of the PTS-GFL superfamily. It includes several sequenced fructose, mannose and mannitol-specific porters, as well as several putative PTS porters of unknown specificities. The fructose porters of this family phosphorylate fructose on the 1-position. Those of TC family 4.A.6 phosphorylate fructose on the 6-position.

The PTS Lactose-N,N’-Diacetylchitobiose (Lac) Family includes several sequenced lactose porters of Gram-positive bacteria, as well as the Escherichia coli and Borrelia burgdorferi N,N'-diacetylchitobiose (Chb) porters. It is part of the PTS-GFL superfamily. The former can transport aromatic β-glucosides and cellobiose, as well as Chb. However, only Chb induces expression of the chb operon.

The PTS Glucitol (Gut) Family consists only of glucitol-specific porters, but these occur both in Gram-negative and Gram-positive bacteria. It is part of the PTS-GFL superfamily.

See also

Further reading

Digital object identifier Character string used as a permanent identifier for a digital object, in a format controlled by the International DOI Foundation

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<i>lac</i> operon Set genes encoding proteins and enzymes for lactose metabolism

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PEP group translocation, also known as the phosphotransferase system or PTS, is a distinct method used by bacteria for sugar uptake where the source of energy is from phosphoenolpyruvate (PEP). It is known as multicomponent system that always involves enzymes of the plasma membrane and those in the cytoplasm. The PTS system uses active transport. After the translocation across the membrane, the metabolites transported are modified. The system was discovered by Saul Roseman in 1964. The bacterial phosphoenolpyruvate:sugar phosphotransferase system (PTS) transports and phosphorylates its sugar substrates in a single energy-coupled step. This transport process is dependent on several cytoplasmic phosphoryl transfer proteins - Enzyme I (I), HPr, Enzyme IIA (IIA), and Enzyme IIB (IIB)) as well as the integral membrane sugar permease (IIC).The PTS Enzyme II complexes are derived from independently evolving 4 PTS Enzyme II complex superfamilies, that include the (1) Glucose (Glc),(2) Mannose (Man), (3) Ascorbate-Galactitol (Asc-Gat) and (4) Dihydroxyacetone (Dha) superfamilies.

The Transporter Classification Database is an International Union of Biochemistry and Molecular Biology (IUBMB)-approved classification system for membrane transport proteins, including ion channels.

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Phosphocarrier protein

Phosphocarrier HPr protein is a small cytoplasmic protein that is a component of the phosphoenolpyruvate-dependent sugar phosphotransferase system (PTS).

Lactose permease

Lactose permease is a membrane protein which is a member of the major facilitator superfamily. Lactose permease can be classified as a symporter, which uses the proton gradient towards the cell to transport β-galactosides such as lactose in the same direction into the cell.

Saccharide transporter

The bacterial phosphoenolpyruvate: sugar phosphotransferase system (PTS) is a multi-protein system involved in the regulation of a variety of metabolic and transcriptional processes. The PTS catalyzes the phosphorylation of incoming sugar substrates concomitant with their translocation across the cell membrane. The general mechanism of the PTS is the following: a phosphoryl group from phosphoenolpyruvate (PEP) is transferred to enzyme-I (EI) of PTS which in turn transfers it to a phosphoryl carrier protein (HPr). Phospho-HPr then transfers the phosphoryl group to a sugar-specific permease which consists of at least three structurally distinct domains which can either be fused together in a single polypeptide chain or exist as two or three interactive chains, formerly called enzymes II (EII) and III (EIII). The IIC domain catalyzes the transfer of a phosphoryl group from IIB to the sugar substrate.

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The PTSGlucose-Glucoside (Glc) family includes porters specific for glucose, glucosamine, N-acetylglucosamine and a large variety of α- and β-glucosides, and is part of the PTS-GFL superfamily.

Permease of phosphotransferase system is a superfamily of phosphotransferase enzymes that facilitate the transport of L-ascorbate (A) and galactitol (G). Classification has been established through phylogenic analysis and bioinformatics.

The PTS Galactitol (Gat) Family is part of the PTS-AG superfamily. The biochemistry of this family is poorly defined. The only well-characterized member of this family is the galactitol permease of Escherichia coli. However, a homologous IIC protein from Listeria monocytogenes has been shown to be required for D-arabitol fermentation. It presumably functions together with IIAGat and IIBGat homologues. IICGat is distantly related to IICSgc of E. coli; IIAGat is distantly related to IIASga and IIASgcof E. coli as well as IIAMtl and IIAFru. IIBGat is distantly related to IIBSga and IIBSgc of E. coli. Domains in the LicR/CelR family of transcriptional activators show C-terminal domains exhibiting weak sequence similarity to IIBGat and IIAGat.

The PTS Mannose-Fructose-Sorbose (Man) Family is a group of multicomponent PTS systems that are involved in sugar uptake in bacteria. This transport process is dependent on several cytoplasmic phosphoryl transfer proteins - Enzyme I (I), HPr, Enzyme IIA (IIA), and Enzyme IIB (IIB) as well as the integral membrane sugar permease complex (IICD). It is not part of the PTS-AG or PTS-GFL superfamilies.

References

  1. Chen, Jonathan S.; Reddy, Vamsee; Chen, Joshua H.; Shlykov, Maksim A.; Zheng, Wei Hao; Cho, Jaehoon; Yen, Ming Ren; Saier, Milton H. (2012-01-01). "Phylogenetic Characterization of Transport Protein Superfamilies: Superiority of SuperfamilyTree Programs over Those Based on Multiple Alignments". Journal of Molecular Microbiology and Biotechnology. 21 (3-4): 83–96. doi:10.1159/000334611. ISSN   1464-1801. PMC   3290041 Lock-green.svg. PMID   22286036.
  2. Nguyen, Thai X.; Yen, Ming-Ren; Barabote, Ravi D.; Saier, Milton H. (2006-01-01). "Topological predictions for integral membrane permeases of the phosphoenolpyruvate:sugar phosphotransferase system". Journal of Molecular Microbiology and Biotechnology. 11 (6): 345–360. doi:10.1159/000095636. ISSN   1464-1801. PMID   17114898.