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Mannose is a sugar monomer of the aldohexose series of carbohydrates. It is a C-2 epimer of glucose. Mannose is important in human metabolism, especially in the glycosylation of certain proteins. Several congenital disorders of glycosylation are associated with mutations in enzymes involved in mannose metabolism.
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 to be a multicomponent system that always involves enzymes of the plasma membrane and those in the cytoplasm.
The Transporter Classification Database is an International Union of Biochemistry and Molecular Biology (IUBMB)-approved classification system for membrane transport proteins, including ion channels.
The sodium/phosphate cotransporter is a member of the phosphate:Na+ symporter (PNaS) family within the TOG Superfamily of transport proteins as specified in the Transporter Classification Database (TCDB).
In enzymology, a protein-Npi-phosphohistidine-sugar phosphotransferase is an enzyme that catalyzes the chemical reaction
Phosphocarrier HPr protein is a small cytoplasmic protein that is a component of the phosphoenolpyruvate-dependent sugar phosphotransferase system (PTS).
The Nucleobase cation symporter-2 (NCS2) family, also called the Nucleobase ascorbate transporter (NAT) family, consists of over 1000 sequenced proteins derived from gram-negative and gram-positive bacteria, archaea, fungi, plants and animals. The NCS2/NAT family is a member of the APC Superfamily of secondary carriers. Of the five known families of transporters that act on nucleobases, NCS2/NAT is the only one that is most widespread. Many functionally characterized members are specific for nucleobases including both purines and pyrimidines, but others are purine-specific. However, two closely related rat/human members of the family, SVCT1 and SVCT2, localized to different tissues of the body, co-transport L-ascorbate (vitamin C) and Na+ with a high degree of specificity and high affinity for the vitamin. Clustering of NCS2/NAT family members on the phylogenetic tree is complex, with bacterial proteins and eukaryotic proteins each falling into at least three distinct clusters. The plant and animal proteins cluster loosely together, but the fungal proteins branch from one of the three bacterial clusters forming a tighter grouping. E. coli possesses four distantly related paralogous members of the NCS2 family.
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.
The transporter-opsin-G protein-coupled receptor (TOG) superfamily is a protein superfamily of integral membrane proteins, usually of 7 or 8 transmembrane alpha-helical segments (TMSs). It includes (1) ion-translocating microbial rhodopsins and (2) G protein-coupled receptors (GPCRs), (3) Sweet sugar transporters, (4) nicotinamide ribonucleoside uptake permeases (PnuC; TC# 4.B.1), (5) 4-toluene sulfonate uptake permeases (TSUP); TC# 2.A.102), (6) Ni2+–Co2+ transporters (NiCoT); TC# 2.A.52), (7) organic solute transporters (OST); TC# 2.A.82), (8) phosphate:Na+ symporters (PNaS); TC# 2.A.58) and (9) lysosomal cystine transporters (LCT); TC# 2.A.43).
The amino acid-polyamine-organocation (APC) superfamily is the second largest superfamily of secondary carrier proteins currently known, and it contain several Solute carriers. Originally, the APC superfamily consisted of subfamilies under the transporter classification number 2.A.3. This superfamily has since been expanded to include eighteen different families.
The ion transporter (IT) superfamily is a superfamily of secondary carriers that transport charged substrates.
The lactate permease (LctP) family is a family of transport proteins belonging to the ion transporter (IT) superfamily.
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.
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.
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.
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 L-Ascorbate (L-Asc) Family includes porters specific for L-ascorbate, and is part of the PTS-AG superfamily. A single PTS permease of the L-Asc family of PTS permeases has been functionally characterized. This is the SgaTBA system, renamed UlaABC by Yew and Gerlt.
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
- ↑ Chen JS, Reddy V, Chen JH, Shlykov MA, Zheng WH, Cho J, Yen MR, Saier MH (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. PMC 3290041 . PMID 22286036.
- ↑ Nguyen TX, Yen MR, Barabote RD, Saier MH (2006-01-01). "Topological predictions for integral membrane permeases of the phosphoenolpyruvate:sugar phosphotransferase system". Journal of Molecular Microbiology and Biotechnology. 11 (6): 345–60. doi:10.1159/000095636. PMID 17114898.
- ↑ Luo P, Yu X, Wang W, Fan S, Li X, Wang J (March 2015). "Crystal structure of a phosphorylation-coupled vitamin C transporter". Nature Structural & Molecular Biology. 22 (3): 238–41. doi:10.1038/nsmb.2975. PMID 25686089.
- ↑ Luo P, Dai S, Zeng J, Duan J, Shi H, Wang J (2018). "Inward-facing conformation of l-ascorbate transporter suggests an elevator mechanism". Cell Discovery. 4: 35. doi:10.1038/s41421-018-0037-y. PMC 6048161 . PMID 30038796.