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J Biol Chem. 2015 Jan 2;290(1):505-19. doi: 10.1074/jbc.M114.616847. Epub 2014 Nov 5.

O-fucose monosaccharide of Drosophila Notch has a temperature-sensitive function and cooperates with O-glucose glycan in Notch transport and Notch signaling activation.

Author information

1
From the Department of Biological Science and Technology, Tokyo University of Science, 6-3-1 Niijuku, Katsushika-ku, Tokyo, 125-1500, the Department of Biological Sciences, Graduate School of Science, Osaka University, 1-1 Machikaneyama, Toyonaka, Osaka 560-0043.
2
the Department of Biological Sciences, Graduate School of Science, Osaka University, 1-1 Machikaneyama, Toyonaka, Osaka 560-0043.
3
From the Department of Biological Science and Technology, Tokyo University of Science, 6-3-1 Niijuku, Katsushika-ku, Tokyo, 125-1500.
4
Genome and Drug Research Center, Tokyo University of Science, 2641 Yamazaki, Noda, Chiba, 278-8510, the Graduate School of Science,Chiba University, 1-33 Yayoi, Inage, Chiba, and.
5
the Department of Biochemistry II, Nagoya University Graduate School of Medicine, Tsurumai, Showa-ku, Nagoya 466-0065, Japan.
6
the Department of Biological Sciences, Graduate School of Science, Osaka University, 1-1 Machikaneyama, Toyonaka, Osaka 560-0043, kmatsuno@bio.sci.osaka-u.ac.jp.

Abstract

Notch (N) is a transmembrane receptor that mediates the cell-cell interactions necessary for many cell fate decisions. N has many epidermal growth factor-like repeats that are O-fucosylated by the protein O-fucosyltransferase 1 (O-Fut1), and the O-fut1 gene is essential for N signaling. However, the role of the monosaccharide O-fucose on N is unclear, because O-Fut1 also appears to have O-fucosyltransferase activity-independent functions, including as an N-specific chaperon. Such an enzymatic activity-independent function could account for the essential role of O-fut1 in N signaling. To evaluate the role of the monosaccharide O-fucose modification in N signaling, here we generated a knock-in mutant of O-fut1 (O-fut1(R245A knock-in)), which expresses a mutant protein that lacks O-fucosyltransferase activity but maintains the N-specific chaperon activity. Using O-fut1(R245A knock-in) and other gene mutations that abolish the O-fucosylation of N, we found that the monosaccharide O-fucose modification of N has a temperature-sensitive function that is essential for N signaling. The O-fucose monosaccharide and O-glucose glycan modification, catalyzed by Rumi, function redundantly in the activation of N signaling. We also showed that the redundant function of these two modifications is responsible for the presence of N at the cell surface. Our findings elucidate how different forms of glycosylation on a protein can influence the protein's functions.

KEYWORDS:

Cell Signaling; Drosophila; Endoplasmic Reticulum (ER); Glycosylation; Notch; O-Fucose; O-Fucosyltransferase 1; O-Glucose; Rumi; Trafficking

PMID:
25378397
PMCID:
PMC4281752
DOI:
10.1074/jbc.M114.616847
[Indexed for MEDLINE]
Free PMC Article

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