title: Arabidopsis auxin-resistance gene AXR1 encodes a protein related to ubiquitin-activating enzyme E1.
abstract: The plant hormone auxin has a central role in many aspects of plant growth and development. By screening for mutants of Arabidopsis that are resistant to exogenous auxin, we have identified several genes that are required for normal auxin response. One of these genes, AXR1, is defined by recessive mutations that confer auxin resistance to the roots, rosettes and inflorescences of mutant plants. In addition, axr1 mutants display a variety of morphological defects that are consistent with a reduction in auxin sensitivity. Here we isolate the AXR1 gene using a map-based approach and report that AXR1 encodes a new protein with significant sequence similarity to the ubiquitin-activating enzyme E1. The AXR1 protein is highly diverged from previously characterized E1 enzymes, however, and lacks a key cysteine residue that is essential for E1 activity. AXR1 may therefore define a new class of enzymes in the ubiquitin pathway or it may have a novel function in cellular regulation which is unrelated to ubiquitin conjugation.
authors.affiliation: Department of Biology, Indiana University, Bloomington 47405.
authors.forename: H M
authors.initials: HM
authors.lastname: Leyser
authors.forename: C A
authors.initials: CA
authors.lastname: Lincoln
authors.forename: C
authors.initials: C
authors.lastname: Timpte
authors.forename: D
authors.initials: D
authors.lastname: Lammer
authors.forename: J
authors.initials: J
authors.lastname: Turner
authors.forename: M
authors.initials: M
authors.lastname: Estelle
mesh_terms: D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000187:drug effects / Q000235:genetics*; D029681:Arabidopsis Proteins; D002874:Chromosome Mapping; D003360:Cosmids; D004351:Drug Resistance / Q000235:genetics; D017343:Genes, Plant; D006133:Growth Substances; D007210:Indoleacetic Acids / Q000494:pharmacology*; D008025:Ligases / Q000737:chemistry; D008969:Molecular Sequence Data; D009154:Mutation; D010940:Plant Proteins / Q000737:chemistry / Q000235:genetics*; D017386:Sequence Homology, Amino Acid; D044764:Ubiquitin-Activating Enzymes; D044767:Ubiquitin-Protein Ligases
chemical_list: C081977:AXR1 protein, Arabidopsis; D029681:Arabidopsis Proteins; D006133:Growth Substances; D007210:Indoleacetic Acids; D010940:Plant Proteins; D044767:Ubiquitin-Protein Ligases; D008025:Ligases; D044764:Ubiquitin-Activating Enzymes