AXL and AXR1 have redundant functions in RUB conjugation and growth and development in Arabidopsis

作者：Nihal Dharmasiri, Sunethra Dharmasiri, Dolf Weijers, Nirmala Karunarathna, Gerd Jürgens, Mark Estelle · 发表于：The Plant Journal · 年份：2007 · DOI：10.1111/j.1365-313x.2007.03211.x · 被引用次数：71 · 研究领域：Ubiquitin and proteasome pathways、Plant Molecular Biology Research、Microtubule and mitosis dynamics

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.