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An N‐Terminal Dileucine Motif Directs Two‐Pore Channels to the Tonoplast of Plant Cells
Author(s) -
Larisch Nina,
Schulze Christina,
Galione Antony,
Dietrich Petra
Publication year - 2012
Publication title -
traffic
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.677
H-Index - 130
eISSN - 1600-0854
pISSN - 1398-9219
DOI - 10.1111/j.1600-0854.2012.01366.x
Subject(s) - biology , vacuole , microbiology and biotechnology , protein targeting , endosome , arabidopsis , protein sorting signals , signal transducing adaptor protein , transport protein , organelle , cytoplasm , transmembrane protein , vacuolar protein sorting , membrane protein , mutant , biochemistry , peptide sequence , signal transduction , signal peptide , gene , membrane , receptor , intracellular
Two‐pore channels ( TPCs ) constitute a family of endolysosomal cation channels with functions in Ca 2+ signaling. We used a mutational analysis to investigate the role of channel domains for the trafficking of the Arabidopsis TPC1 to the tonoplast, a process that is generally not well understood in plants. The results show that the soluble C‐terminus was not essential for targeting but for channel function, while further C‐terminal truncations of two or more transmembrane domains impaired protein trafficking. An N‐terminal dileucine motif ( EDPLI ) proved to be critical for vacuolar targeting of TPC1 , which was independent of the adaptor protein AP ‐3. Deletion or mutation of this sorting motif, which is conserved among TPCs caused redirection of the protein transport to the plasma membrane. An N‐terminal region with a predicted α‐helical structure was shown to support efficient vacuolar trafficking and was essential for TPC1 function. Similar to their localization in mammalian endosomes and lysosomes, MmTPC1 and MmTPC2 were targeted to small organelles and the membrane of the lytic vacuole, respectively, when expressed in plant cells. These results shed new light on the largely uncharacterized sorting signals of plant tonoplast proteins and reveal similarities between the targeting machinery of plants and mammals.