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A delayed leaf senescence mutant is defective in arginyl‐tRNA:protein arginyltransferase, a component of the N‐end rule pathway in Arabidopsis
Author(s) -
Yoshida Satoko,
Ito Masaki,
Callis Judy,
Nishida Ikuo,
Watanabe Akira
Publication year - 2002
Publication title -
the plant journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.058
H-Index - 269
eISSN - 1365-313X
pISSN - 0960-7412
DOI - 10.1046/j.1365-313x.2002.01407.x
Subject(s) - mutant , biology , senescence , arabidopsis , gene , wild type , mutation , genetics , microbiology and biotechnology , biochemistry
Summary We have isolated a delayed‐leaf‐senescence mutant, designated dls1 , from an Arabidopsis T‐DNA line. Leaf senescence progresses more slowly in the dls1 mutant than in the wild‐type plant in both age‐dependent and dark‐induced senescence. Genetic analysis revealed that the dls1 is a monogenic recessive mutation that cosegregated with the T‐DNA insertion. Isolation of DNA flanking the T‐DNA revealed that the T‐DNA was inserted into the fourth intron of the AtATE1 gene, which encodes arginyl‐tRNA:protein arginyltransferase (E C . 2.3.2.8, R‐transferase), a component of the N‐end rule proteolytic pathway in yeast and mammals that transfers arginine to the N‐terminus of proteins with N‐terminal glutamyl or aspartyl residues. AtATE1 transcripts were not detectable in the dls1 mutant by RT‐PCR analysis. Introduction of a wild‐type AtATE1 gene into the dls1 mutant complemented the dls1 phenotype. We also showed using a transient expression assay system, that the dls1 mutation results in a decreased degradation of proteins with Asp or Glu at their N‐termini, and that the introduction of the wild‐type AtATE1 gene reverses this deficiency. These results suggest that the normal progression of leaf senescence requires R‐transferase activity, and that proteolysis by the N‐end rule pathway has an important physiological function in the progress of leaf senescence in plants.