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17 results on '"Komarova, Nataliya Y"'

1. Stress-regulated Arabidopsis GAT2 is a low affinity γ-aminobutyric acid transporter.

Author

Meier, Stefan, Bautzmann, Robin, Komarova, Nataliya Y, Ernst, Viona, Grotemeyer, Marianne Suter, Schröder, Kirsten, Haindrich, Alexander C, Fernández, Adriana Vega, Robert, Christelle A M, Ward, John M, and Rentsch, Doris

Subjects
MEMBRANE potential, GABA transporters, PLANT growth, POLYETHYLENE glycol, AMINO acids
Abstract

The four-carbon non-proteinogenic amino acid γ-aminobutyric acid (GABA) accumulates to high levels in plants in response to various abiotic and biotic stress stimuli, and plays a role in C:N balance, signaling, and as a transport regulator. Expression in Xenopus oocytes and voltage-clamping allowed the characterization of Arabidopsis GAT2 (At5g41800) as a low affinity GABA transporter with a K 0.5 G A B A ~8 mM. l -Alanine and butylamine represented additional substrates. GABA-induced currents were strongly dependent on the membrane potential, reaching the highest affinity and highest transport rates at strongly negative membrane potentials. Mutation of Ser17, previously reported to be phosphorylated in planta, did not result in altered affinity. In a short-term stress experiment, AtGAT2 mRNA levels were up-regulated at low water potential and under osmotic stress (polyethylene glycol and mannitol). Furthermore, AtGAT2 promoter activity was detected in vascular tissues, maturating pollen, and the phloem unloading region of young seeds. Even though this suggested a role for AtGAT2 in long-distance transport and loading of sink organs, under the conditions tested neither AtGAT2 -overexpressing plants, atgat2 or atgat1 T-DNA insertion lines, nor atgat1 atgat2 doubleknockout mutants differed from wild-type plants in growth on GABA, amino acid levels, or resistance to salt and osmotic stress. [ABSTRACT FROM AUTHOR]

Published
2024
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11. Determinants for Arabidopsis peptide transporter targeting to the tonoplast or plasma membrane

Author

Komarova Nataliya Y., Meier Stefan, Meier Anna, Grotemeyer Marianne Suter, and Rentsch Doris

Subjects
Arabidopsis Proteins, Protoplasts, Recombinant Fusion Proteins, Amino Acid Motifs, Cell Membrane, Molecular Sequence Data, Arabidopsis, Membrane Transport Proteins, Saccharomyces cerevisiae, Protein Sorting Signals, Protein Transport, Microscopy, Fluorescence, Tobacco, Vacuoles, Mutagenesis, Site-Directed, Amino Acid Sequence, Plant Proteins
Abstract

Di- and tripeptide transporters of the PTR/NRT1 (peptide transporter/nitrate transporter1)-family are localized either at the tonoplast (TP) or plasma membrane (PM). As limited information is available on structural determinants required for targeting of plant membrane proteins, we performed gene shuffling and domain swapping experiments of Arabidopsis PTRs. A 7 amino acid fragment of the hydrophilic N-terminal region of PTR2, PTR4 and PTR6 was required for TP localization and sufficient to redirect not only PM-localized PTR1 or PTR5, but also sucrose transporter SUC2 to the TP. Alanine scanning mutagenesis identified L(11) and I(12) of PTR2 to be essential for TP targeting, while only one acidic amino acid at position 5, 6 or 7 was required, revealing a dileucine (LL or LI) motif with at least one upstream acidic residue. Similar dileucine motifs could be identified in other plant TP transporters, indicating a broader role of this targeting motif in plants. Targeting to the PM required the loop between transmembrane domain 6 and 7 of PTR1 or PTR5. Deletion of either PM or TP targeting signals resulted in retention in internal membranes, indicating that PTR trafficking to these destination membranes requires distinct signals and is in both cases not by default.

Published
2011

14. Comparative genomics and functional analysis of the NiaP family uncover nicotinate transporters from bacteria, plants, and mammals.

Author

University of Florida - Fifield, Jeanguenin, Linda, Lara-Núñez, Aurora, Rodionov, Dmitry A, Osterman, Andrei L, Komarova, Nataliya Y, Rentsch, Doris, Gregory, Jesse F, Hanson, Andrew D, University of Florida - Fifield, Jeanguenin, Linda, Lara-Núñez, Aurora, Rodionov, Dmitry A, Osterman, Andrei L, Komarova, Nataliya Y, Rentsch, Doris, Gregory, Jesse F, and Hanson, Andrew D

Abstract

The transporter(s) that mediate uptake of nicotinate and its N-methyl derivative trigonelline are not known in plants, and certain mammalian nicotinate transporters also remain unidentified. Potential candidates for these missing transporters include proteins from the ubiquitous NiaP family. In bacteria, niaP genes often belong to NAD-related regulons, and genetic evidence supports a role for Bacillus subtilis and Acinetobacter baumannii NiaP proteins in uptake of nicotinate or nicotinamide. Other bacterial niaP genes are, however, not in NAD-related regulons but cluster on the chromosome with choline-related (e.g., Ralstonia solanacearum and Burkholderia xenovorans) or thiamin-related (e.g., Thermus thermophilus) genes, implying that they might encode transporters for these compounds. Radiometric uptake assays using Lactococcus lactis cells expressing NiaP proteins showed that B. subtilis, R. solanacearum, and B. xenovorans NiaP transport nicotinate via an energy-dependent mechanism. Likewise, NiaP proteins from maize (GRMZM2G381453, GRMZM2G066801, and GRMZM2G081774), Arabidopsis (At3g13050), and mouse (SVOP) transported nicotinate; the Arabidopsis protein also transported trigonelline. In contrast, T. thermophilus NiaP transported only thiamin. None of the proteins tested transported choline or the thiazole and pyrimidine products of thiamin breakdown. The maize and Arabidopsis NiaP proteins are the first nicotinate transporters reported in plants, the Arabidopsis protein is the first trigonelline transporter, and mouse SVOP appears to represent a novel type of mammalian nicotinate transporter. More generally, these results indicate that specificity for nicotinate is conserved widely, but not absolutely, among pro- and eukaryotic NiaP family proteins.

Published
2012

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