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Arabidopsis ubiquitin‐specific proteases UBP12 and UBP13 shape ORE1 levels during leaf senescence induced by nitrogen deficiency
Author(s) -
Park SuHyun,
Jeong Jin Seo,
Seo Jun Sung,
Park Bong Soo,
Chua NamHai
Publication year - 2019
Publication title -
new phytologist
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.742
H-Index - 244
eISSN - 1469-8137
pISSN - 0028-646X
DOI - 10.1111/nph.15879
Subject(s) - senescence , biology , ubiquitin ligase , microbiology and biotechnology , transcription factor , arabidopsis , ubiquitin , cycloheximide , biochemistry , gene , mutant , protein biosynthesis
Summary Nitrogen deficiency (−N) in plants triggers leaf senescence which is regulated by the transcription factor ORE1. Little is known about post‐translational regulation of ORE1 in this process. Here, we show that UBP12/UBP13 (ubiquitin‐specific protease 12/13) antagonize the action of NLA (nitrogen limitation adaptation) E3 ligase to maintain ORE1 homeostasis. In vitro pull‐down and in vivo co‐immunoprecipitation assays demonstrated specific binding between UBP12/UBP13 and ORE1. We further analyzed in various genotypes total Chl content and expression levels of senescence‐related genes under −N conditions. We found that UBP12/UBP13 can deubiquitinate polyubiquitinated ORE1 in vitro and increase the stability of ORE1 in vivo in MG132/cycloheximide‐chase experiments. Plants overexpressing UBP12 / UBP13 display accelerated leaf senescence which is reversed by the ore1 mutation. By contrast, the senescence phenotype of plants overexpressing ORE1 is exacerbated by UBP12 / UBP13 overexpression. The expression of senescence‐related genes tracks the senescence phenotype. ORE1 protein levels can be elevated by UBP12 / UBP13 overexpression but decreased in ubp12‐2w/13‐3 . In conclusion, UBP12/UBP13 deubiquitinate ORE1 to stabilize this transcription factor and promote its activity as a positive regulator for leaf senescence under −N conditions. Our study shows that UBP12/UBP13 counteracts the effect of NLA E3 ligase to accelerate leaf senescence under nitrogen starvation.