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Evidence for potassium transport activity of Arabidopsis KEA1-KEA6.
Sci Rep. 2019 07 11; 9(1):10040.SR

Abstract

Arabidopsis thaliana contains the putative K+ efflux transporters KEA1-KEA6, similar to KefB and KefC of Escherichia coli. KEA1-KEA3 are involved in the regulation of photosynthetic electron transport and chloroplast development. KEA4-KEA6 mediate pH regulation of the endomembrane network during salinity stress. However, the ion transport activities of KEA1-KEA6 have not been directly characterized. In this study, we used an E. coli expression system to examine KEA activity. KEA1-KEA3 and KEA5 showed bi-directional K+ transport activity, whereas KEA4 and KEA6 functioned as a K+ uptake system. The thylakoid membrane-localized Na+/H+ antiporter NhaS3 from the model cyanobacterium Synechocystis is the closest homolog of KEA3. Changing the putative Na+/H+ selective site of KEA3 (Gln-Asp) to that of NhaS3 (Asp-Asp) did not alter the ion selectivity without loss of K+ transport activity. The first residue in the conserved motif was not a determinant for K+ or Na+ selectivity. Deletion of the possible nucleotide-binding KTN domain from KEA3 lowered K+ transport activity, indicating that the KTN domain was important for this function. The KEA3-G422R mutation discovered in the Arabidopsis dpgr mutant increased K+ transport activity, consistent with the mutant phenotype. These results indicate that Arabidopsis KEA1-KEA6 act as K+ transport systems, and support the interpretation that KEA3 promotes dissipation of ΔpH in the thylakoid membrane.

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Authors+Show Affiliations

Tsujii M
Department of Biomolecular Engineering, Graduate School of Engineering, Tohoku University, Aobayama 6-6-07, Sendai, 980-8579, Japan.
Kera K
Department of Biomolecular Engineering, Graduate School of Engineering, Tohoku University, Aobayama 6-6-07, Sendai, 980-8579, Japan.
Hamamoto S
Department of Biomolecular Engineering, Graduate School of Engineering, Tohoku University, Aobayama 6-6-07, Sendai, 980-8579, Japan.
Kuromori T
RIKEN Center for Sustainable Resource Science, Wako, Saitama, 351-0198, Japan.
Shikanai T
Department of Botany, Graduate School of Science, Kyoto University, Kyoto, 606-8502, Japan.
Uozumi N
Department of Biomolecular Engineering, Graduate School of Engineering, Tohoku University, Aobayama 6-6-07, Sendai, 980-8579, Japan. uozumi@tohoku.ac.jp.

MeSH

AntiportersArabidopsisArabidopsis ProteinsIon TransportPotassiumPotassium-Hydrogen AntiportersProtein Isoforms

Pub Type(s)

Journal Article
Research Support, Non-U.S. Gov't

Language

eng

PubMed ID

31296940

Citation

Tsujii, Masaru, et al. "Evidence for Potassium Transport Activity of Arabidopsis KEA1-KEA6." Scientific Reports, vol. 9, no. 1, 2019, p. 10040.
Tsujii M, Kera K, Hamamoto S, et al. Evidence for potassium transport activity of Arabidopsis KEA1-KEA6. Sci Rep. 2019;9(1):10040.
Tsujii, M., Kera, K., Hamamoto, S., Kuromori, T., Shikanai, T., & Uozumi, N. (2019). Evidence for potassium transport activity of Arabidopsis KEA1-KEA6. Scientific Reports, 9(1), 10040. https://doi.org/10.1038/s41598-019-46463-7
Tsujii M, et al. Evidence for Potassium Transport Activity of Arabidopsis KEA1-KEA6. Sci Rep. 2019 07 11;9(1):10040. PubMed PMID: 31296940.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Evidence for potassium transport activity of Arabidopsis KEA1-KEA6. AU - Tsujii,Masaru, AU - Kera,Kota, AU - Hamamoto,Shin, AU - Kuromori,Takashi, AU - Shikanai,Toshiharu, AU - Uozumi,Nobuyuki, Y1 - 2019/07/11/ PY - 2019/03/22/received PY - 2019/06/24/accepted PY - 2019/7/13/entrez PY - 2019/7/13/pubmed PY - 2020/10/22/medline SP - 10040 EP - 10040 JF - Scientific reports JO - Sci Rep VL - 9 IS - 1 N2 - Arabidopsis thaliana contains the putative K+ efflux transporters KEA1-KEA6, similar to KefB and KefC of Escherichia coli. KEA1-KEA3 are involved in the regulation of photosynthetic electron transport and chloroplast development. KEA4-KEA6 mediate pH regulation of the endomembrane network during salinity stress. However, the ion transport activities of KEA1-KEA6 have not been directly characterized. In this study, we used an E. coli expression system to examine KEA activity. KEA1-KEA3 and KEA5 showed bi-directional K+ transport activity, whereas KEA4 and KEA6 functioned as a K+ uptake system. The thylakoid membrane-localized Na+/H+ antiporter NhaS3 from the model cyanobacterium Synechocystis is the closest homolog of KEA3. Changing the putative Na+/H+ selective site of KEA3 (Gln-Asp) to that of NhaS3 (Asp-Asp) did not alter the ion selectivity without loss of K+ transport activity. The first residue in the conserved motif was not a determinant for K+ or Na+ selectivity. Deletion of the possible nucleotide-binding KTN domain from KEA3 lowered K+ transport activity, indicating that the KTN domain was important for this function. The KEA3-G422R mutation discovered in the Arabidopsis dpgr mutant increased K+ transport activity, consistent with the mutant phenotype. These results indicate that Arabidopsis KEA1-KEA6 act as K+ transport systems, and support the interpretation that KEA3 promotes dissipation of ΔpH in the thylakoid membrane. SN - 2045-2322 UR - https://www.unboundmedicine.com/medline/citation/31296940/Evidence_for_potassium_transport_activity_of_Arabidopsis_KEA1_KEA6_ DB - PRIME DP - Unbound Medicine ER -