A vacuolar carboxypeptidase mutant of Arabidopsis thaliana is degraded by the ERAD pathway independently of its N-glycan

作者：Yamamoto Masaya; Kawanabe Mitsuyoshi; Hayashi Yoko; Endo Toshiya; Nishikawa Shuh ichi^*

来源：Biochemical and Biophysical Research Communications, 2010, 393(3): 384-389.

DOI：10.1016/j.bbrc.2010.02.001

• Endoplasmic reticulum (ER)
• ER-associated degradation (ERAD)
• Arabidopsis thaliana
• Serine carboxypeptidase

Misfolded proteins produced in the endoplasmic reticulum (ER) are degraded by a mechanism, the ER-associated degradation (ERAD). Here we report establishment of the experimental system to analyze the ERAD in plant cells. Carboxypeptidase V (CPY) is a vacuolar enzyme and its mutant CPY* is degraded by the ERAD in yeast. Since Arabidopsis thaliana has AtCPY, an ortholog of yeast CPY, we constructed and expressed fusion proteins consisting of AtCPY and GFP and of AtCPY*, which carries a mutation homologous to yeast CPY* and GFP in A. thaliana cells. While AtCPY-GFP was efficiently transported to the vacuole, AtCPY* -GFP was retained in the ER to be degraded in proteasome- and Cdc48-dependent manners. We also found that AtCPY*-GFP was degraded by the ERAD in yeast cells, but that its single N-glycan did not function as a degradation signal in yeast or plant cells. Therefore, AtCPY*-GFP can be used as a marker protein to analyze the ERAD pathway, likely for nonglycosylated substrates, in plant cells.

• 出版日期2010-3-12