Golgi 1,4-fucosyltransferase of Arabidopsis thaliana partially localizes at the nuclear envelope

作者：Rips Stephan; Frank Manuel; Elting Annegret; Offenborn Jan Niklas; von Schaewen Antje^*

来源：Traffic, 2017, 18(10): 646-657.

DOI：10.1111/tra.12506

• Arabidopsis thaliana
• glycoprotein modification
• Golgi-type complex N-glycans
• nuclear envelope
• 1
• 4-fucosyltransferase

We analyzed plant-derived 1,4-fucosyltransferase (FucTc) homologs by reporter fusions and focused on representatives of the Brassicaceae and Solanaceae. Arabidopsis thalianaAtFucTc-green fluorescent protein (GFP) or tomato LeFucTc-GFP restored Lewis-a formation in a fuctc mutant, confirming functionality in the trans-Golgi. AtFucTc-GFP partly accumulated at the nuclear envelope (NE) not observed for other homologs or truncated AtFucTc lacking the N-terminus or catalytic domain. Analysis of At/LeFucTc-GFPswap constructs with exchanged cytosolic, transmembrane and stalk (CTS), or only the CT regions, revealed that sorting information resides in the membrane anchor. Other domains of AtFuctc also contribute, since amino-acid changes in the CT region strongly reduced but did not abolish NE localization. By contrast, two N-terminal GFP copies did, indicating localization at the inner nuclear membrane (INM). Tunicamycin treatment of AtFucTc-GFP abolished NE localization and enhanced overlap with an endosomal marker, suggesting involvement of N-glycosylation. Yet neither expression in protoplasts of Arabidopsis N-glycosylation mutants nor elimination of the N-glycosylation site in AtFucTc prevented perinuclear accumulation. Disruption of endoplasmic reticulum (ER)-to-Golgi transport by co-expression of Sar1(H74L) trapped tunicamycin-released AtFucTc-GFP in the ER, however, without NE localization. Since recovery after tunicamycin-washout required de novo-protein synthesis, our analyses suggest that AtFucTc localizes to the NE/INM due to interaction with an unknown (glyco)protein.

• 出版日期2017-10