Hormone signaling through protein destruction: a lesson from plants.
Ubiquitin-dependent protein degradation has emerged as a major pathway regulating eukaryotic biology. By employing a variety of ubiquitin ligases to target specific cellular proteins, the ubiquitin-proteasome system controls physiological processes in a highly regulated fashion. Recent studies on a plant hormone auxin have unveiled a novel paradigm of signal transduction in which ubiquitin ligases function as hormone receptors. Perceived by the F-box protein subunit of the SCF(TIR1) ubiquitin ligase, auxin directly promotes the recruitment of a family of transcriptional repressors for ubiquitination, thereby activating extensive transcriptional programs. Structural studies have revealed that auxin functions through a "molecular glue" mechanism to enhance protein-protein interactions with the assistance of another small molecule cofactor, inositol hexakisphosphate. Given the extensive repertoire of similar ubiquitin ligases in eukaryotic cells, this novel and widely adopted hormone-signaling mechanism in plants may also exist in other organisms.
Tan
Xu
X
Dept. of Pharmacology, Box 357280, Univ. of Washington, Seattle, WA 98195, USA.
Zheng
Ning
N
D000818:Animals; D006728:Hormones / Q000502:physiology*; D006801:Humans; D007210:Indoleacetic Acids / Q000494:pharmacology; D053858:Metabolic Networks and Pathways / Q000187:drug effects / Q000502:physiology*; D008954:Models, Biological; D008958:Models, Molecular; D018521:Plant Physiological Phenomena; D010944:Plants / Q000378:metabolism*; D046988:Proteasome Endopeptidase Complex / Q000502:physiology; D011499:Protein Processing, Post-Translational / Q000187:drug effects / Q000502:physiology*; D044767:Ubiquitin-Protein Ligases / Q000502:physiology; D054875:Ubiquitination / Q000502:physiology
D006728:Hormones; D007210:Indoleacetic Acids; D044767:Ubiquitin-Protein Ligases; D046988:Proteasome Endopeptidase Complex