title: HOS1 Facilitates the Phytochrome B-Mediated Inhibition of PIF4 Function during Hypocotyl Growth in Arabidopsis.
abstract: Upon exposure to light, developing seedlings undergo photomorphogenesis, as illustrated by inhibition of hypocotyl elongation, cotyledon opening, and leaf greening. During hypocotyl photomorphogenesis, light signals are sensed by multiple photoreceptors, among which the red/far-red light-sensing phytochromes have been extensively studied. However, it is not fully understood how the phytochromes modulate hypocotyl growth. Here, we demonstrated that HIGH EXPRESSION OF OSMOTICALLY RESPONSIVE GENES 1 (HOS1), which is known to either act as E3 ubiquitin ligase or affect chromatin organization, inhibits the transcriptional activation activity of PHYTOCHROME INTERACTING FACTOR 4 (PIF4), a key transcription factor that promotes hypocotyl growth. Consistent with the negative regulatory role of HOS1 in hypocotyl growth, HOS1-defective mutants exhibited elongated hypocotyls in the light. Notably, phyB induces HOS1 activity in inhibiting PIF4 function. Taken together, these observations provide a molecular basis for the phyB-mediated suppression of hypocotyl growth in Arabidopsis.
authors.affiliation: Department of Chemistry, Seoul National University, Seoul 08826, Korea.
authors.forename: Ju-Heon
authors.initials: JH
authors.lastname: Kim
authors.affiliation: Department of Chemistry, Seoul National University, Seoul 08826, Korea.
authors.forename: Hyo-Jun
authors.initials: HJ
authors.lastname: Lee
authors.affiliation: Sainsbury Laboratory, University of Cambridge, Cambridge CB2 1LR, UK.
authors.forename: Jae-Hoon
authors.initials: JH
authors.lastname: Jung
authors.affiliation: Department of Chemistry, Seoul National University, Seoul 08826, Korea.
authors.forename: Sangmin
authors.initials: S
authors.lastname: Lee
authors.affiliation: Department of Chemistry, Seoul National University, Seoul 08826, Korea; Plant Genomics and Breeding Institute, Seoul National University, Seoul 08826, Korea. Electronic address: cmpark@snu.ac.kr.
authors.forename: Chung-Mo
authors.initials: CM
authors.lastname: Park
mesh_terms: D017360:Arabidopsis / Q000254:growth & development / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D051792:Basic Helix-Loop-Helix Proteins / Q000378:metabolism*; D018506:Gene Expression Regulation, Plant; D018546:Hypocotyl / Q000254:growth & development* / Q000378:metabolism; D047908:Intracellular Signaling Peptides and Proteins / Q000235:genetics / Q000378:metabolism*; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism*; D051939:Phytochrome B / Q000378:metabolism; D015398:Signal Transduction
chemical_list: D029681:Arabidopsis Proteins; D051792:Basic Helix-Loop-Helix Proteins; D047908:Intracellular Signaling Peptides and Proteins; D009687:Nuclear Proteins; D051939:Phytochrome B; C425768:HOS1 protein, Arabidopsis; C459466:PIF4 protein, Arabidopsis
keywords: HOS1; PIF4; hypocotyl growth; photomorphogenesis; phytochrome signaling