Browse
Submit Data
Databases
API
Help

Dataset Information

0 Views

0 Connections

0 Citations

0 Reanalyses

0 Downloads

Omics score: 0

Mutation of the proton-coupled folate transporter gene (PCFT-SLC46A1) in Turkish siblings with hereditary folate malabsorption.

ABSTRACT: Hereditary folate malabsorption (HFM) is a rare autosomal recessive disorder characterized by systemic and central nervous system folate deficiency. Turkish siblings are reported with the clinical syndrome of HFM, homozygous for deletion of 2 bases (c.204_205 delCC) within the first exon of the proton-coupled folate transporter (PCFT) gene, causing a frameshift. Low blood and cerebrospinal fluid folate levels were detected at ages 3.5 and 1 month. Treatment with parenteral 5-formyltetrahydrofolate resulted in normal development now at ages 3 and 1 year. Extending current knowledge on the phenotypic manifestations of HFM and the PCFT mutation spectrum will provide opportunities to define possible genotype-phenotype correlations and clarify the basis for the phenotypic variability that is characteristic of this disorder.

SUBMITTER: Atabay B

PROVIDER: S-EPMC3885236 | biostudies-literature | 2010 Nov

REPOSITORIES: biostudies-literature

ACCESS DATA

Json Xml

Publications

Mutation of the proton-coupled folate transporter gene (PCFT-SLC46A1) in Turkish siblings with hereditary folate malabsorption.

Atabay Berna B Turker Meral M Ozer Esra Arun EA Mahadeo Kris K Diop-Bove Ndeye N Goldman I David ID

Pediatric hematology and oncology 20101101 8

Hereditary folate malabsorption (HFM) is a rare autosomal recessive disorder characterized by systemic and central nervous system folate deficiency. Turkish siblings are reported with the clinical syndrome of HFM, homozygous for deletion of 2 bases (c.204_205 delCC) within the first exon of the proton-coupled folate transporter (PCFT) gene, causing a frameshift. Low blood and cerebrospinal fluid folate levels were detected at ages 3.5 and 1 month. Treatment with parenteral 5-formyltetrahydrofola ...[more]

PMID: 20795774

Similar Datasets

Functional roles of aspartate residues of the proton-coupled folate transporter (PCFT-SLC46A1); a D156Y mutation causing hereditary folate malabsorption.

Project description:The proton-coupled folate transporter (PCFT; SLC46A1) mediates folate transport into enterocytes in the proximal small intestine; pcft loss-of-function mutations are the basis for hereditary folate malabsorption. The current study explored the roles of Asp residues in PCFT function. A novel, homozygous, loss-of-function mutation, D156Y, was identified in a child of Pakistani origin with hereditary folate malabsorption. Of the 6 other conserved Asp residues, only one, D109, is shown to be required for function. D156Y, along with a variety of other substitutions at this site (Trp, Phe, Val, Asn, or Lys), lacked function due to instability of the PCFT protein. Substantial function was preserved with Glu, Gly, and, to a lesser extent, with Ser, Thr, and Ala substitutions. This correlated with PCFT bio-tinylated at the cell surface. In contrast, all D109 mutants, including D109E, lacked function irrespective of pH (4.5, 5.5, and 7.4) or substrate concentration (0.5-100 ?M), despite surface expression comparable to wild-type PCFT. Hence, D156 plays a critical role in PCFT protein stability, and D109, located in the first intracellular loop between the second and third transmembrane domains, is absolutely required for PCFT function.

| S-EPMC3012536 | biostudies-literature

A novel deletion mutation in the proton-coupled folate transporter (PCFT; SLC46A1) in a Nicaraguan child with hereditary folate malabsorption.

Project description:Hereditary folate malabsorption (OMIM 229050) is a rare autosomal recessive disorder caused by loss-of-function mutations in the proton-coupled folate transporter gene (pcft/SLC46A1) resulting in impaired folate transport across the intestine and into the central nervous system. We report a novel, homozygous, deletion mutation in a child of Nicaraguan descent in exon 2 (c.558-588 del, ss778190447) at amino acid position I188 resulting in a frameshift with a premature stop.

| S-EPMC3836604 | biostudies-literature

Properties of the Arg376 residue of the proton-coupled folate transporter (PCFT-SLC46A1) and a glutamine mutant causing hereditary folate malabsorption.

Project description:The proton-coupled folate transporter (PCFT-SLC46A1) is required for intestinal folate absorption and is mutated in the autosomal recessive disorder, hereditary folate malabsorption (HFM). This report characterizes properties and requirements of the R376 residue in PCFT function, including a R376Q mutant associated with HFM. Gln, Cys, and Ala substitutions resulted in markedly impaired transport of 5-formyltetrahydrofolate (5-FTHF) and 5-methyltetrahydrofolate (5-MTHF) due to an increase in K(m) and decrease in V(max) in HeLa R1-11 transfectants lacking endogenous folate transport function. In contrast, although the influx K(m) for pemetrexed was increased, transport was fully preserved at saturating concentrations and enhanced for the like-charged R376K- and R376H-PCFT. Pemetrexed and 5-FTHF influx mediated by R376Q-PCFT was markedly decreased at pH 5.5 compared with wild-type PCFT. However, while pemetrexed transport was substantially preserved at low pH (4.5-5.0), 5-FTHF transport remained very low. Electrophysiological studies in Xenopus oocytes demonstrated that 1) the R376Q mutant, like wild-type PCFT, transports protons in the absence of folate substrate, and in this respect has channel-like properties; and 2) the influx K(m) mediated by R376Q-PCFT is increased for 5-MTHF, 5-FTHF, and pemetrexed. The data suggest that mutation of the R376 residue to Gln impairs proton binding which, in turn, modulates the folate-binding pocket and depresses the rate of conformational alteration of the carrier, a change that appears to be, in part, substrate dependent.

| S-EPMC2980313 | biostudies-literature

Prevalence of a loss-of-function mutation in the proton-coupled folate transporter gene (PCFT-SLC46A1) causing hereditary folate malabsorption in Puerto Rico.

Project description:ObjectiveTo determine whether subjects of Puerto Rican heritage are at increased risk for a specific mutation of the proton-coupled folate transporter (PCFT) causing hereditary folate malabsorption (HFM).Study designThree percent of the births in Puerto Rico in 2005, with additional regional oversampling, were screened for the prevalence of the c.1082G>A; p.Y362_G389 del PCFT gene mutation. Six new subjects of Puerto Rican heritage with the clinical diagnosis of HFM were also assessed for this mutation.ResultsSix subjects of Puerto Rican heritage with the clinical diagnosis of HFM were all homozygous for the c.1082G>A; p.Y362_G389 del PCFT mutation. Three heterozygote carriers were identified from the 1582 newborn samples randomly selected from births in Puerto Rico in 2005. The carrier frequency for the mutated allele was 0.2% island-wide and 6.3% in Villalba.ConclusionThese findings are consistent with a common mutation in the PCFT gene causing HFM that has disseminated to Puerto Ricans who have migrated to mainland United States. Because prompt diagnosis and treatment of infants with HFM can prevent the consequences of this disorder, newborn screening should be considered in high-risk populations and physicians should be aware of its prevalence in infants of Puerto Rican ancestry.

| S-EPMC3935241 | biostudies-literature

Hereditary folate malabsorption due to a mutation in the external gate of the proton-coupled folate transporter SLC46A1.

Project description:Hereditary folate malabsorption (HFM) is an autosomal recessive disorder characterized by impaired intestinal folate absorption and impaired folate transport across the choroid plexus due to loss of function of the proton-coupled folate transporter (PCFT-SLC46A1). We report a novel mutation, causing HFM, affecting a residue located in the 11th transmembrane helix within the external gate. The mutant N411K-PCFT was stable, trafficked to the cell membrane, and had sufficient residual activity to characterize the transport defect and the structural requirements at this site for gate function. The influx Vmax of the N411K mutant was markedly decreased, as was the affinity for most, but not all, folate/antifolate substrates. The greatest loss of activity was for 5-methyltetrahydrofolate. Substitutions with positive charged residues resulted in a loss of activity (arginine > lysine > histidine). Function was retained for the negative charged aspartate, but not the larger glutamate substitutions, whereas the bulky hydrophobic (leucine), or polar (glutamine) substitutions, were tolerated. Homology models of PCFT, in the inward and outward open conformations, based upon the mammalian Glut5 fructose transporter structures, localize Asn411 protruding into the aqueous pathway. This is most prominent when the carrier is in the inward open conformation when the external gate is closed. Mutations at this site likely result in highly specific steric and electrostatic interactions between the Asn411-substituted, and other, residues in the gate region that impede carrier function. The substrate specificity of the N411K mutant may be due to alterations of substrate flows through the external gate, downstream allosteric alterations in the folate-binding pocket, or both.

| S-EPMC5761628 | biostudies-literature

Substitutions that lock and unlock the proton-coupled folate transporter (PCFT-SLC46A1) in an inward-open conformation.

Project description:The proton-coupled folate transporter (PCFT) mediates intestinal absorption of folates and their transport from blood to cerebrospinal fluid across the choroid plexus. Substitutions at Asp-109 in the first intracellular loop between the first and second transmembrane domains (TMDs) abolish PCFT function, but protein expression and trafficking to the cell membrane are retained. Here, we used site-directed mutagenesis, the substituted-cysteine accessibility method, functional analyses, and homology modeling to determine whether the D109A substitution locks PCFT in one of its conformational states. Cys-substituted residues lining the PCFT aqueous translocation pathway and accessible in WT PCFT to the membrane-impermeable cysteine-biotinylation reagent, MTSEA-biotin, lost accessibility when introduced into the D109A scaffold. Substitutions at Gly-305 located exofacially within the eighth TMD, particularly with bulky residues, when introduced into the D109A scaffold largely restored function and MTSEA-biotin accessibility to Cys-substituted residues within the pathway. Likewise, Ser-196 substitution in the fifth TMD, predicted by homology modeling to be in proximity to Gly-305, also partially restored function found in solute transporters, is critical to oscillation of the carrier among its conformational states. Substitutions at Asp-109 and Gly-112 lock PCFT in an inward-open conformation, resulting in the loss of function. However, the integrity of the locked protein is preserved, indicated by the restoration of function after insertion of a second "unlocking" mutation. and accessibility. Similarly, the inactivating G112K substitution within the first intracellular loop was partially reactivated by introducing the G305L substitution. These data indicate that the first intracellular loop, with a sequence identical to "motif A" (GXXXDXXGR(R/K)).

| S-EPMC6509503 | biostudies-literature

Identification of an Extracellular Gate for the Proton-coupled Folate Transporter (PCFT-SLC46A1) by Cysteine Cross-linking.

Project description:The proton-coupled folate transporter (PCFT, SLC46A1) is required for intestinal folate absorption and folate homeostasis in humans. A homology model of PCFT, based upon theEscherichia coliglycerol 3-phosphate transporter structure, predicted that PCFT transmembrane domains (TMDs) 1, 2, 7, and 11 form an extracellular gate in the inward-open conformation. To assess this model, five residues (Gln(45)-TMD1, Asn(90)-TMD2, Leu(290)-TMD7, Ser(407)-TMD11 and Asn(411)-TMD11) in the predicted gate were substituted with Cys to generate single and nine double mutants. Transport function of the mutants was assayed in transient transfectants by measurement of [(3)H]substrate influx as was accessibility of the Cys residues to biotinylation. Pairs of Cys residues were assessed for spontaneous formation of a disulfide bond, induction of a disulfide bond by oxidization with dichloro(1,10-phenanthroline)copper (II) (CuPh), or the formation of a Cd(2+)complex. The data were consistent with the formation of a spontaneous disulfide bond between the N90C/S407C pair and a CuPh- and Cd(2+)-induced disulfide bond and complex, respectively, for the Q45C/L290C and L290C/N411C pairs. The decrease in activity induced by cross-linkage of the Cys residue pairs was due to a decrease in the influxVmaxconsistent with restriction in the mobility of the transporter. The presence of folate substrate decreased the CuPh-induced inhibition of transport. Hence, the data support the glycerol 3-phosphate transporter-based homology model of PCFT and the presence of an extracellular gate formed by TMDs 1, 2, 7, and 11.

| S-EPMC4825018 | biostudies-literature

Expression in Sf9 insect cells, purification and functional reconstitution of the human proton-coupled folate transporter (PCFT, SLC46A1).

Project description:The proton-coupled folate transporter (PCFT) provides an essential uptake route for the vitamin folic acid (B9) in mammals. In addition, it is currently of high interest for targeting chemotherapeutic agents to tumors due to the increased folic acid requirement of rapidly dividing tumor cells as well as the upregulated PCFT expression in several tumors. To understand its function, determination of its atomic structure and molecular mechanism of transport are essential goals that require large amounts of functional PCFT. Here, we present a high-level heterologous expression system for human PCFT using a recombinant baculovirus and Spodoptera frugiperda (Sf9) insect cells. We demonstrate folate transport functionality along the PCFT expression, isolation, and purification process. Importantly, purified PCFT transports folic acid after reconstitution. We thus succeeded in overcoming heterologous expression as a major bottleneck of PCFT research. The availability of an overexpression system for human PCFT provides the basis for future biochemical, biophysical and structural studies.

| S-EPMC5426777 | biostudies-literature

Identification of a functionally critical GXXG motif and its relationship to the folate binding site of the proton-coupled folate transporter (PCFT-SLC46A1).

Project description:The proton-coupled folate transporter (PCFT) mediates intestinal folate absorption, and loss-of-function mutations in this gene result in the autosomal recessive disorder hereditary folate malabsorption. The current study, focused on a structure-functional analysis of this transporter, identified Gly-189 and Gly-192 (a GxxG motif) located in the fifth transmembrane domain as residues that could not be replaced with alanine without a loss of function. In contrast, function was preserved when Gly-56 and Gly-59 (the other conservative GXXG motif in human PCFT) were replaced with alanine. Similarly, Gly-93 and Gly-97, which constitute the only conserved GXXXG dimerization motif in human PCFT, tolerated alanine substitution. To explore the role of this region in folate binding, the residues around Gly-189 and Gly-192 were analyzed by the substituted cysteine accessibility method. Both I188C and M193C mutants were functional and were inhibited by membrane-impermeable sulfhydryl-reactive reagents; this could be prevented with PCFT substrate, but the protection was sustained at 0°C only for the I188C mutant, consistent with localization of Ile-188 in the PCFT folate binding pocket. The functional role of residues around Gly-189 and Gly-192 is consistent with a molecular structural model in which these two residues along with Ieu-188 are accessible to the PCFT aqueous translocation pathway.

| S-EPMC3468349 | biostudies-literature

Hereditary folate malabsorption with a novel mutation on SLC46A1: A case report.

Project description:RationaleHereditary folate malabsorption (HFM) is characterized by folate deficiency with impaired intestinal folate absorption and impaired folate transport into the central nervous system. Its manifestations mainly include macrocytic anemia, recurrent infections, and neurological deficits. The neurological manifestations include progressive psychomotor retardation, behavioral disorders, and early-onset seizures.Patient concernsFrom early infancy, a Chinese boy had experienced macrocytic anemia, leukopenia, thrombocytopenia, recurrent pneumonia, diarrhea, and mouth ulcers. He also presented with progressive neurological symptoms.DiagnosisA novel mutation in the SLC46A1 gene was identified, and HFM was diagnosed at 18 months of age.InterventionsAfter the HFM diagnosis, the boy was treated with folinic acid.LessonsFolinic acid supplementation is effective and may offer life-changing therapy for patients with HFM.

| S-EPMC5815676 | biostudies-literature

OmicsDI is part of the ELIXIR infrastructure

OmicsDI is an Elixir interoperability service. Learn more ›

Tweets

OmicsDI Databases

PRIDE
PeptideAtlas
MassIVE
JPOST Repository
Physiome Model Repository

EGA
EVA
ENA
LINCS
PAXDB
Cell Collective

MetaboLights
Metabolomics Workbench
MetabolomeExpress
GNPS
BioModels
FAIRDOMHub

ArrayExpress
dbGaP
ExpressionAtlas
GEO
NODE

Information

Databases
Help
API
Contact us
Code on GitHub
Terms of use
Submit Data