Inorganic phosphate transporter family

Last updated

The inorganic phosphate transporter (PiT) family is a group of carrier proteins derived from Gram-negative and Gram-positive bacteria, archaea, and eukaryotes.

Contents

Function

Functionally-characterized members of the family appear to catalyze inorganic phosphate (Pi) or inorganic sulfate uptake either by H+ or Na+ symport. Both PitA (TC# 2.A.20.1.1) and PitB (TC# 2.A.20.1.2) of E. coli probably catalyze metal ion·phosphate:H+ symport, where Mg2+, Ca2+ or Zn2+ (and probably other divalent cations) can complex with Pi. The mammalian proteins (i.e., TC# 2.A.20.2.7) have been reported to function as viral receptors, but they undoubtedly function as transport proteins as well. For numerous gammaretroviruses, such as the gibbon ape leukemia virus, woolly monkey virus, feline leukemia virus subgroup B, feline leukemia virus subgroup T, and 10A1 murine leukemia virus, this receptor is the human type III sodium-dependent inorganic phosphate transporter, SLC20A1, also known as PiT1. [1]

The malaria parasite, Plasmodium falciparum , grows within its host erythrocyte and induces an increase in the permeability of the erythrocyte membrane to a range of solutes including Na+ and K+. This results in a progressive increase in the concentration of Na+ in the erythrocyte cytosol. The parasite cytosol has a relatively low Na+ concentration, generating a large inward Na+ gradient across the parasite plasma membrane. Saliba et al. (2006) showed that the parasite exploits the Na+ electrochemical gradient to energize the uptake of inorganic phosphate (Pi) with a stoichiometry of 2Na+:1Pi and with an apparent preference for the monovalent over the divalent form of Pi (see TC #2.A.20.2.5).

The generalized transport reactions possibly catalyzed by members of the PiT family are:

  1. HPO2−
    4     (out) + [nH+ or Na+] (out) → HPO2−
    4     (in) + [nH+ or Na+] (in)
  2. Me2+ · HPO2−
    4     (out) + nH+ (out) → Me2+ · HPO2−
    4     (in) + nH+ (in)
  3. SO2−
    4     (out) + nH+ (out) → SO2−
    4     (in) + nH+ (in).

Structure

The molecular sizes of Pit family members are reported to vary from 354 to 681 residues (10-12 TMSs) with the mammalian and Plasmodium proteins exhibiting the largest sizes. The sulfate permease of B. subtilis, CysP, is of 354 residues with 11 putative TMSs. [2] As of early 2016, it appears no crystal structures are available for PiT proteins.

Phylogeny

Phylogenetic grouping of the phosphate transport proteins generally correlates with organismal phylogeny. Thus the fungal, plant, animal and archaeal proteins each cluster separately. [3] However, the tree exhibits two clusters of bacterial phosphate transport proteins. One bacterial cluster is distant from the eukaryotic proteins while the other cluster is close to the plant proteins. Both clusters include proteins from Gram-negative and Gram-positive bacteria. The sulfate permease, CysP (TC# 2.A.20.4.1), is distantly related to the phosphate permeases.

Members of the PiT family arose by a tandem internal gene duplication event. Surprisingly, TopPred predicts a 12 TMS topology for the yeast Pho89 protein, but the homologous regions are not predicted to show similar topological features. [4] [5]

See also

Related Research Articles

Glucose transporter 1, also known as solute carrier family 2, facilitated glucose transporter member 1 (SLC2A1), is a uniporter protein that in humans is encoded by the SLC2A1 gene. GLUT1 facilitates the transport of glucose across the plasma membranes of mammalian cells. This gene encodes a major glucose transporter in the mammalian blood-brain barrier. The encoded protein is found primarily in the cell membrane and on the cell surface, where it can also function as a receptor for human T-cell leukemia virus (HTLV) I and II. One good source of GLUT1 is erythrocyte membranes. GLUT1 accounts for 2 percent of the protein in the plasma membrane of erythrocytes. GLUT1, found in the plasma membrane of erythrocytes, is a classic example of a uniporter. After glucose is transported into the erythrocyte, it is rapidly phosphorylated, forming glucose-6-phosphate, which cannot leave the cell. Mutations in this gene can cause GLUT1 deficiency syndrome 1, GLUT1 deficiency syndrome 2, idiopathic generalized epilepsy 12, dystonia 9, and stomatin-deficient cryohydrocytosis.

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).

Mitochondrial carrier

Mitochondrial carriers are proteins from solute carrier family 25 which transfer molecules across the membranes of the mitochondria. Mitochondrial carriers are also classified in the Transporter Classification Database. The Mitochondrial Carrier (MC) Superfamily has been expanded to include both the original Mitochondrial Carrier (MC) family and the Mitochondrial Inner/Outer Membrane Fusion (MMF) family.

Translocase is a general term for a protein that assists in moving another molecule, usually across a cell membrane. These enzymes catalyze the movement of ions or molecules across membranes or their separation within membranes. The reaction is designated as a transfer from “side 1” to “side 2” because the designations “in” and “out”, which had previously been used, can be ambiguous. Translocases are the most common secretion system in Gram positive bacteria.

SLC20A1

Sodium-dependent phosphate transporter 1 is a protein that in humans is encoded by the SLC20A1 gene.

SLC20A2

Sodium-dependent phosphate transporter 2 is a protein that in humans is encoded by the SLC20A2 gene.

The Nucleobase:Cation Symporter-1 (NCS1) Family (TC# 2.A.39) consists of over 1000 currently sequenced proteins derived from Gram-negative and Gram-positive bacteria, archaea, fungi and plants. These proteins function as transporters for nucleobases including purines and pyrimidines. Members of this family possess twelve transmembrane α-helical spanners (TMSs). At least some of them have been shown to function in uptake by substrate:H+ symport mechanism.

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).

Phosphate permeases are membrane transport proteins that facilitate the diffusion of phosphate into and out of a cell or organelle. Some of these families include:

The ion transporter (IT) superfamily is a superfamily of secondary carriers that transport charged substrates.

The Citrate-Mg2+:H+ (CitM) / Citrate-Ca2+:H+ (CitH) Symporter (CitMHS) Family (TC# 2.A.11) is a family of transport proteins belonging to the Ion transporter superfamily. Members of this family are found in Gram-positive and Gram-negative bacteria, archaea and possibly eukaryotes. These proteins all probably arose by an internal gene duplication event. Lensbouer & Doyle (2010) have reviewed these systems, classifying the porters with three superfamilies, according to ion-preference:

The lactate permease (LctP) family is a family of transport proteins belonging to the ion transporter (IT) superfamily.

The Pho1 phosphate permease family is a family of phosphate transporters belonging to the ion transporter (IT) superfamily. Representative members of the Pho1 family include the putative phosphate transporter PHO1 of Arabidopsis thaliana, and the xenotropic and polytropic murine-leukemia virus receptor Xpr1 of Culex pipiens.

The Malonate Uptake (MatC) family is a constituent of the ion transporter (IT) superfamily. It consists of proteins from Gram-negative and Gram-positive bacteria, simple eukaryotes and archaea. The proteins are of about 450 amino acyl residues in length with 12-14 putative transmembrane segments (TMSs). Closest functionally-characterized homologues are in the DASS family. One member of this family is a putative malonate transporter.

The NhaB family belongs to the ion transporter (IT) superfamily. A representative list of proteins belonging to the NhaB family can be found in the Transporter Classification Database.

The NhaD family belongs to the Ion Transporter (IT) Superfamily. A representative list of proteins belonging to the NhaD family can be found in the Transporter Classification Database.

The NhaE family belongs to the Ion Transporter (IT) Superfamily. A representative list of proteins belonging to the NhaE family can be found in the Transporter Classification Database.

The Monovalent Cation (K+ or Na+):Proton Antiporter-3 (CPA3) Family (TC# 2.A.63) is a member of the Na+ transporting Mrp superfamily. The CPA3 family consists of bacterial multicomponent K+:H+ and Na+:H+ antiporters. The best characterized systems are the PhaABCDEFG system of Sinorhizobium meliloti (TC# 2.A.63.1.1) that functions in pH adaptation and as a K+ efflux system, and the MnhABCDEFG system of Staphylococcus aureus (TC# 2.A.63.1.3) that functions as a Na+ efflux Na+:H+ antiporter.

Members of the H+, Na+-translocating Pyrophosphatase (M+-PPase) Family (TC# 3.A.10) are found in the vacuolar (tonoplast) membranes of higher plants, algae, and protozoa, and in both bacteria and archaea. They are therefore ancient enzymes.

The K+Transporter (Trk) Family is a member of the voltage-gated ion channel (VIC) superfamily. The proteins of the Trk family are derived from Gram-negative and Gram-positive bacteria, yeast and plants.

References

  1. ↑ Farrell, Karen B.; Tusnady, Gabor E.; Eiden, Maribeth V. (2009-10-23). "New structural arrangement of the extracellular regions of the phosphate transporter SLC20A1, the receptor for gibbon ape leukemia virus". The Journal of Biological Chemistry. 284 (43): 29979–29987. doi: 10.1074/jbc.M109.022566 . ISSN   1083-351X. PMC   2785626 . PMID   19717569.
  2. ↑ Mansilla, M. C.; de Mendoza, D. (2000-04-01). "The Bacillus subtilis cysP gene encodes a novel sulphate permease related to the inorganic phosphate transporter (Pit) family". Microbiology. 146 (4): 815–821. doi: 10.1099/00221287-146-4-815 . ISSN   1350-0872. PMID   10784039.
  3. ↑ Saier, M. H.; Eng, B. H.; Fard, S.; Garg, J.; Haggerty, D. A.; Hutchinson, W. J.; Jack, D. L.; Lai, E. C.; Liu, H. J. (1999-02-25). "Phylogenetic characterization of novel transport protein families revealed by genome analyses". Biochimica et Biophysica Acta (BBA) - Reviews on Biomembranes. 1422 (1): 1–56. doi:10.1016/s0304-4157(98)00023-9. ISSN   0006-3002. PMID   10082980.
  4. ↑ Persson, B. L.; Berhe, A.; Fristedt, U.; Martinez, P.; Pattison, J.; Petersson, J.; Weinander, R. (1998-06-10). "Phosphate permeases of Saccharomyces cerevisiae". Biochimica et Biophysica Acta (BBA) - Bioenergetics. 1365 (1–2): 23–30. doi: 10.1016/s0005-2728(98)00037-1 . ISSN   0006-3002. PMID   9693717.
  5. ↑ Persson, B. L.; Petersson, J.; Fristedt, U.; Weinander, R.; Berhe, A.; Pattison, J. (1999-11-16). "Phosphate permeases of Saccharomyces cerevisiae: structure, function and regulation". Biochimica et Biophysica Acta (BBA) - Reviews on Biomembranes. 1422 (3): 255–272. doi:10.1016/s0304-4157(99)00010-6. ISSN   0006-3002. PMID   10548719.

As of this edit, this article uses content from "2.A.20 The Inorganic Phosphate Transporter (PiT) Family" , which is licensed in a way that permits reuse under the Creative Commons Attribution-ShareAlike 3.0 Unported License, but not under the GFDL. All relevant terms must be followed.

This page is based on this Wikipedia article
Text is available under the CC BY-SA 4.0 license; additional terms may apply.
Images, videos and audio are available under their respective licenses.