Jen1p: A High Affinity Selenite Transporter in Yeast

Selenium is a micronutrient in most eukaryotes, including humans, which is well known for having an extremely thin border between beneficial and toxic concentrations. Soluble tetravalent selenite is the predominant environmental form and also the form that is applied in the treatment of human diseases. To acquire this nutrient from low environmental concentrations as well as to avoid toxicity, a well-controlled transport system is required. Here we report that Jen1p, a proton-coupled monocarboxylate transporter in S. cerevisiae, catalyzes high-affinity uptake of selenite. Disruption of JEN1 resulted in selenite resistance, and overexpression resulted in selenite hypersensitivity. Transport assay showed that overexpression of Jen1p enables selenite accumulation in yeast compared with a JEN1 knock out strain, indicating the Jen1p transporter facilitates selenite accumulation inside cells. Selenite uptake by Jen1p had a Kmof 0.91 mM, which is comparable to the Kmfor lactate. Jen1p transported selenite in a proton-dependent manner which resembles the transport mechanism for lactate. In addition, selenite and lactate can inhibit the transport of each other competitively. Therefore, we postulate selenite is a molecular mimic of monocarboxylates which allows selenite to be transported by Jen1p.

Download Full-text

The structural basis for high‐affinity uptake of lignin‐derived aromatic compounds by proteobacterial TRAP transporters

FEBS Journal ◽

10.1111/febs.16156 ◽

2021 ◽

Author(s):

Claudine Bisson ◽

Robert C. Salmon ◽

Laura West ◽

John B. Rafferty ◽

Andrew Hitchcock ◽

...

Keyword(s):

Aromatic Compounds ◽

Structural Basis ◽

High Affinity ◽

High Affinity Uptake

Download Full-text

Ca2+-Dependent Protein Kinase 6 Enhances KAT2 Shaker Channel Activity in Arabidopsis thaliana

International Journal of Molecular Sciences ◽

10.3390/ijms22041596 ◽

2021 ◽

Vol 22 (4) ◽

pp. 1596

Author(s):

Elsa Ronzier ◽

Claire Corratgé-Faillie ◽

Frédéric Sanchez ◽

Christian Brière ◽

Tou Cheu Xiong

Keyword(s):

Arabidopsis Thaliana ◽

Resonance Energy Transfer ◽

Resonance Energy ◽

Physical Interaction ◽

Fluorescence Lifetime Imaging ◽

Dependent Manner ◽

In Planta ◽

Knock Out ◽

Calcium Dependent ◽

Dependent Protein

Post-translational regulations of Shaker-like voltage-gated K+ channels were reported to be essential for rapid responses to environmental stresses in plants. In particular, it has been shown that calcium-dependent protein kinases (CPKs) regulate Shaker channels in plants. Here, the focus was on KAT2, a Shaker channel cloned in the model plant Arabidopsis thaliana, where is it expressed namely in the vascular tissues of leaves. After co-expression of KAT2 with AtCPK6 in Xenopuslaevis oocytes, voltage-clamp recordings demonstrated that AtCPK6 stimulates the activity of KAT2 in a calcium-dependent manner. A physical interaction between these two proteins has also been shown by Förster resonance energy transfer by fluorescence lifetime imaging (FRET-FLIM). Peptide array assays support that AtCPK6 phosphorylates KAT2 at several positions, also in a calcium-dependent manner. Finally, K+ fluorescence imaging in planta suggests that K+ distribution is impaired in kat2 knock-out mutant leaves. We propose that the AtCPK6/KAT2 couple plays a role in the homeostasis of K+ distribution in leaves.

Download Full-text

Inhibition of receptor binding and neutralization of bioactivity by anti-erythropoietin monoclonal antibodies

Blood ◽

10.1182/blood.v75.4.874.874 ◽

1990 ◽

Vol 75 (4) ◽

pp. 874-880 ◽

Cited By ~ 13

Author(s):

AD D'Andrea ◽

PJ Szklut ◽

HF Lodish ◽

EM Alderman

Keyword(s):

Monoclonal Antibodies ◽

Receptor Binding ◽

Sodium Dodecyl ◽

Dependent Manner ◽

Epo Receptor ◽

High Affinity ◽

Group I ◽

Dependent Cell ◽

Group Ii ◽

Murine Erythroleukemia

Abstract We have generated four high affinity monoclonal antibodies (MoAbs) to recombinant human erythropoietin (EPO). All four MoAbs immunoprecipitate radioiodinated native EPO, and the concentrations of MoAbs required for maximum binding range from 10 nmol/L to 100 nmol/L. Two MoAbs, designated Group I MoAbs, bind to an epitope within the N- terminal 20 amino acids of EPO and also immunoprecipitate sodium dodecyl sulfate (SDS)-denatured EPO. Two other MoAbs (Group II MoAbs) do not immunoprecipitate SDS-denatured EPO and do not bind to any of the eight endo C fragments of EPO. We first used murine erythroleukemia (MEL) cells to test the MoAbs for inhibition of EPO-receptor binding. MEL cells, although unresponsive to EPO, express 760 high affinity receptors for EPO per cell (Kd = 0.24 nmol/L). To assay our MoAbs, MEL cells were grown as monolayers on fibronectin-coated Petri dishes and incubated at 4 degrees C with radioiodinated EPO. Group I MoAbs do not inhibit binding of radioiodinated EPO to the MEL EPO-receptor, but Group II MoAbs do inhibit binding in a dose-dependent manner. We next examined the neutralization of EPO bioactivity by our MoAbs, using EPO- dependent cell line. Only Group II MoAbs inhibit a newly developed EPO- dependent cell growth, demonstrating that inhibition of EPO-receptor binding correlates with neutralization of EPO bioactivity.

Download Full-text

Monocarboxylate transporter 4 (MCT4) is a high affinity transporter capable of exporting lactate in high-lactate microenvironments

Journal of Biological Chemistry ◽

10.1074/jbc.ra119.009093 ◽

2019 ◽

Vol 294 (52) ◽

pp. 20135-20147 ◽

Cited By ~ 13

Author(s):

Yasna Contreras-Baeza ◽

Pamela Y. Sandoval ◽

Romina Alarcón ◽

Alex Galaz ◽

Francisca Cortés-Molina ◽

...

Keyword(s):

Monocarboxylate Transporter ◽

High Affinity ◽

High Lactate ◽

Monocarboxylate Transporter 4

Download Full-text

Lack of a high affinity transport system for dopamine in the median eminence and posterior pituitary

Brain Research ◽

10.1016/0006-8993(79)91060-6 ◽

1979 ◽

Vol 171 (3) ◽

pp. 545-551 ◽

Cited By ~ 80

Author(s):

K.T. Demarest ◽

K.E. Moore

Keyword(s):

Transport System ◽

Median Eminence ◽

Posterior Pituitary ◽

High Affinity

Download Full-text

The effect of polychlorinated biphenyls on the high affinity uptake of the neurotransmitters, dopamine, serotonin, glutamate and GABA, into rat brain synaptosomes

Toxicology ◽

10.1016/s0300-483x(00)00374-7 ◽

2001 ◽

Vol 159 (1-2) ◽

pp. 11-21 ◽

Cited By ~ 104

Author(s):

Espen Mariussen ◽

Frode Fonnum

Keyword(s):

Polychlorinated Biphenyls ◽

Rat Brain ◽

Rat Brain Synaptosomes ◽

High Affinity ◽

High Affinity Uptake ◽

Brain Synaptosomes

Download Full-text

Regulation of the High-Affinity Nitrate Transport System in Wheat Roots by Exogenous Abscisic Acid and Glutamine

Journal of Integrative Plant Biology ◽

10.1111/j.1744-7909.2007.00485.x ◽

2007 ◽

Vol 49 (12) ◽

pp. 1719-1725 ◽

Cited By ~ 12

Author(s):

Chao Cai ◽

Xue-Qiang Zhao ◽

Yong-Guan Zhu ◽

Bin Li ◽

Yi-Ping Tong ◽

...

Keyword(s):

Abscisic Acid ◽

Transport System ◽

Nitrate Transport ◽

Wheat Roots ◽

High Affinity

Download Full-text

RCO-3 and COL-26 form an external-to-internal module that regulates the dual-affinity glucose transport system in Neurospora crassa

Biotechnology for Biofuels ◽

10.1186/s13068-021-01877-2 ◽

2021 ◽

Vol 14 (1) ◽

Author(s):

Jinyang Li ◽

Qian Liu ◽

Jingen Li ◽

Liangcai Lin ◽

Xiaolin Li ◽

...

Keyword(s):

Transcription Factor ◽

Neurospora Crassa ◽

Glucose Transport ◽

Transport System ◽

Rational Design ◽

Glucose Sensor ◽

Glucose Transporters ◽

Glucose Fluctuation ◽

High Affinity ◽

Glucose Transport System

Abstract Background Low- and high-affinity glucose transport system is a conserved strategy of microorganism to cope with environmental glucose fluctuation for their growth and competitiveness. In Neurospora crassa, the dual-affinity glucose transport system consists of a low-affinity glucose transporter GLT-1 and two high-affinity glucose transporters HGT-1/HGT-2, which play diverse roles in glucose transport, carbon metabolism, and cellulase expression regulation. However, the regulation of this dual-transporter system in response to environmental glucose fluctuation is not yet clear. Results In this study, we report that a regulation module consisting of a downstream transcription factor COL-26 and an upstream non-transporting glucose sensor RCO-3 regulates the dual-affinity glucose transport system in N. crassa. COL-26 directly binds to the promoter regions of glt-1, hgt-1, and hgt-2, whereas RCO-3 is an upstream factor of the module whose deletion mutant resembles the Δcol-26 mutant phenotypically. Transcriptional profiling analysis revealed that Δcol-26 and Δrco-3 mutants had similar transcriptional profiles, and both mutants had impaired response to a glucose gradient. We also showed that the AMP-activated protein kinase (AMPK) complex is involved in regulation of the glucose transporters. AMPK is required for repression of glt-1 expression in starvation conditions by inhibiting the activity of RCO-3. Conclusions RCO-3 and COL-26 form an external-to-internal module that regulates the glucose dual-affinity transport system. Transcription factor COL-26 was identified as the key regulator. AMPK was also involved in the regulation of the dual-transporter system. Our findings provide novel insight into the molecular basis of glucose uptake and signaling in filamentous fungi, which may aid in the rational design of fungal strains for industrial purposes.

Download Full-text