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AXL and AXR1 have redundant functions in RUB conjugation and growth and development in Arabidopsis
Author(s) -
Dharmasiri Nihal,
Dharmasiri S.,
Weijers D.,
Karunarath.,
Jurgens G.,
Estelle M.
Publication year - 2007
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 - 10.1111/j.1365-313x.2007.03211.x
Subject(s) - cullin , biology , mutant , genetics , gene , microbiology and biotechnology , ubiquitin , ubiquitin ligase
Summary Cullin‐RING ubiquitin‐protein ligases such as the Skp1, cullin, F‐box protein (SCF) have been implicated in many growth and developmental processes in plants. Normal SCF function requires that the CUL1 subunit be post‐translationally modified by related to ubiquitin (RUB), a protein related to ubiquitin. This process is mediated by two enzymes: the RUB‐activating and RUB‐conjugating enzymes. In Arabidopsis, the RUB‐activating enzyme is a heterodimer consisting of AXR1 and ECR1. Mutations in the AXR1 gene result in a pleiotropic phenotype that includes resistance to the plant hormone auxin. Here we report that the AXL ( AXR1‐like ) gene also functions in the RUB conjugation pathway. Overexpression of AXL in the axr1‐3 background complements the axr1‐3 phenotype. Biochemical analysis indicates that AXL overexpression restores CUL1 modification to the wild‐type level, indicating that AXR1 and AXL have the same biochemical activity. Although the axl mutant resembles wild‐type plants, the majority of axr1 axl‐1 double mutants are embryo or seedling lethal. Furthermore, the axl‐1 mutation reveals novel RUB‐dependent processes in embryo development. We conclude that AXR1 and AXL function redundantly in the RUB conjugating pathway.