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Arabinogalactan Glycosyltransferases Target to a Unique Subcellular Compartment That May Function in Unconventional Secretion in Plants.
- Source :
-
Traffic . Nov2014, Vol. 15 Issue 11, p1219-1234. 16p. - Publication Year :
- 2014
-
Abstract
- We report that fluorescently tagged arabinogalactan glycosyltransferases target not only the Golgi apparatus but also uncharacterized smaller compartments when transiently expressed in Nicotiana benthamiana. Approximately 80% of AtGALT31A [ Arabidopsis thaliana galactosyltransferase from family 31 (At1g32930)] was found in the small compartments, of which, 45 and 40% of AtGALT29A [ Arabidopsis thaliana galactosyltransferase from family 29 (At1g08280)] and AtGlcAT14A [ Arabidopsis thaliana glucuronosyltransferase from family 14 (At5g39990)] colocalized with AtGALT31A, respectively; in contrast, N-glycosylation enzymes rarely colocalized (3-18%), implicating a role of the small compartments in a part of arabinogalactan ( O-glycan) biosynthesis rather than N-glycan processing. The dual localization of AtGALT31A was also observed for fluorescently tagged AtGALT31A stably expressed in an Arabidopsis atgalt31a mutant background. Further, site-directed mutagenesis of a phosphorylation site of AtGALT29A ( Y144) increased the frequency of the protein being targeted to the AtGALT31A-localized small compartments, suggesting a role of Y144 in subcellular targeting. The AtGALT31A localized to the small compartments were colocalized with neither SYP61 (syntaxin of plants 61), a marker for trans-Golgi network (TGN), nor FM4-64-stained endosomes. However, 41% colocalized with EXO70E2 ( Arabidopsis thaliana exocyst protein Exo70 homolog 2), a marker for exocyst-positive organelles, and least affected by Brefeldin A and Wortmannin. Taken together, AtGALT31A localized to small compartments that are distinct from the Golgi apparatus, the SYP61-localized TGN, FM4-64-stained endosomes and Wortmannin-vacuolated prevacuolar compartments, but may be part of an unconventional protein secretory pathway represented by EXO70E2 in plants. [ABSTRACT FROM AUTHOR]
Details
- Language :
- English
- ISSN :
- 13989219
- Volume :
- 15
- Issue :
- 11
- Database :
- Academic Search Index
- Journal :
- Traffic
- Publication Type :
- Academic Journal
- Accession number :
- 98949914
- Full Text :
- https://doi.org/10.1111/tra.12203