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Göteborgs universitets publikationer

Plastidial transporters KEA1, -2, and -3 are essential for chloroplast osmoregulation, integrity, and pH regulation in Arabidopsis.

Författare och institution:
Hans-Henning Kunz (-); Markus Gierth (-); Andrei Herdean (Institutionen för biologi och miljövetenskap); Mio Satoh-Cruz (-); DM Kramer (-); Cornelia Spetea (Institutionen för biologi och miljövetenskap); Julian I Schroeder (-)
Publicerad i:
Proceedings of the National Academy of Science of the United States of America, 111 ( 20 ) s. 7480-7485
Artikel, refereegranskad vetenskaplig
Sammanfattning (abstract):
Multiple K+ transporters and channels and the corresponding mutants have been described and studied in the plasma membrane and organelle membranes of plant cells. However, knowledge about the molecular identity of chloroplast K+ transporters is limited. Potassium transport and a well-balanced K+ homeostasis were suggested to play important roles in chloroplast function. Because no loss-of-function mutants have been identified, the importance of K+ transporters for chloroplast function and photosynthesis remains to be determined. Here, we report single and higher-order loss-of-function mutants in members of the cation/proton antiporters-2 antiporter superfamily KEA1, KEA2, and KEA3. KEA1 and KEA2 proteins are targeted to the inner envelope membrane of chloroplasts, whereas KEA3 is targeted to the thylakoid membrane. Higher-order but not single mutants showed increasingly impaired photosynthesis along with pale green leaves and severely stunted growth. The pH component of the proton motive force across the thylakoid membrane was significantly decreased in the kea1kea2 mutants, but increased in the kea3 mutant, indicating an altered chloroplast pH homeostasis. Electron microscopy of kea1kea2 leaf cells revealed dramatically swollen chloroplasts with disrupted envelope membranes and reduced thylakoid membrane density. Unexpectedly, exogenous NaCl application reversed the observed phenotypes. Furthermore, the kea1kea2 background enables genetic analyses of the functional significance of other chloroplast transporters as exemplified here in kea1kea2Na+/H+ antiporter1 (nhd1) triple mutants. Taken together, the presented data demonstrate a fundamental role of inner envelope KEA1 and KEA2 and thylakoid KEA3 transporters in chloroplast osmoregulation, integrity, and ion and pH homeostasis.
Ämne (baseras på Högskoleverkets indelning av forskningsämnen):
Biologiska vetenskaper
chloroplast; potassium transport; photosynthesis; osmoregulation
Postens nummer:
Posten skapad:
2014-05-07 21:06
Posten ändrad:
2016-08-24 13:07

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