AtCAP2 is crucial for lytic vacuole biogenesis during germination by positively regulating vacuolar protein trafficking

Protein trafficking is a fundamental mechanism of subcellular organization and contributes to organellar biogenesis. AtCAP2 is an Arabidopsis homolog of the Mesembryanthemum crystallinum calcium-dependent protein kinase 1 adaptor protein 2 (McCAP2), a member of the syntaxin superfamily. Here, we sho...

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Published inProceedings of the National Academy of Sciences - PNAS Vol. 115; no. 7; pp. E1675 - E1683
Main Authors Kwon, Yun, Shen, Jinbo, Lee, Myoung Hui, Geem, Kyoung Rok, Jiang, Liwen, Hwang, Inhwan
Format Journal Article
LanguageEnglish
Published United States National Academy of Sciences 13.02.2018
SeriesPNAS Plus
Subjects
Acidification
Biological Sciences
Biosynthesis
Calcium
Developmental stages
Flowers & plants
Fusion protein
Germination
Glyceraldehyde-3-phosphate dehydrogenase
Homology
Membrane proteins
Mutation
PNAS Plus
Polyvinyl chloride
Protein kinase
Protein transport
Proteins
Syntaxin
intracellular trafficking
vacuolar trafficking
vacuolar pH
lytic vacuole transition
GAPC2 trafficking
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Summary:Protein trafficking is a fundamental mechanism of subcellular organization and contributes to organellar biogenesis. AtCAP2 is an Arabidopsis homolog of the Mesembryanthemum crystallinum calcium-dependent protein kinase 1 adaptor protein 2 (McCAP2), a member of the syntaxin superfamily. Here, we show that AtCAP2 plays an important role in the conversion to the lytic vacuole (LV) during early plant development. The AtCAP2 loss-of-function mutant atcap2-1 displayed delays in protein storage vacuole (PSV) protein degradation, PSV fusion, LV acidification, and biosynthesis of several vacuolar proteins during germination. At the mature stage, atcap2-1 plants accumulated vacuolar proteins in the prevacuolar compartment (PVC) instead of the LV. In wild-type plants, AtCAP2 localizes to the PVC as a peripheral membrane protein and in the PVC compartment recruits glyceraldehyde-3-phosphate dehydrogenase C2 (GAPC2) to the PVC. We propose that AtCAP2 contributes to LV biogenesis during early plant development by supporting the trafficking of specific proteins involved in the PSV-to-LV transition and LV acidification during early stages of plant development.
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Edited by Natasha V. Raikhel, Center for Plant Cell Biology, Riverside, CA, and approved December 29, 2017 (received for review October 9, 2017)
Author contributions: Y.K., L.J., and I.H. designed research; Y.K., J.S., M.H.L., and K.R.G. performed research; Y.K., J.S., and I.H. analyzed data; and Y.K., L.J., and I.H. wrote the paper.
ISSN:0027-8424
1091-6490
DOI:10.1073/pnas.1717204115