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Auxin is a major plant hormone that controls most aspects of plant growth and development. Auxin is perceived by two distinct classes of receptors: transport inhibitor response 1 (TIR1, or auxin-related F-box (AFB)) and auxin/indole-3-acetic acid (AUX/IAA) coreceptors, that control transcriptional responses to auxin, and the auxin-binding protein 1 (ABP1), that controls a wide variety of growth and developmental processes. To date, the mode of action of ABP1 is still poorly understood and its functional interaction with TIR1/AFB-AUX/IAA coreceptors remains elusive. Here we combine genetic and biochemical approaches to gain insight into the integration of these two pathways. We find that ABP1 is genetically upstream of TIR1/AFBs; ABP1 knockdown leads to an enhanced degradation of AUX/IAA repressors, independently of its effects on endocytosis, through the SCF(TIR1/AFB) E3 ubiquitin ligase pathway. Combining positive and negative regulation of SCF ubiquitin-dependent pathways might be a common mechanism conferring tight control of hormone-mediated responses.
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http://dx.doi.org/10.1038/ncomms3496 | DOI Listing |
Proc Natl Acad Sci U S A
August 2025
Key Laboratory of Structural Biology of Zhejiang Province, School of Life Sciences, Westlake University, Institute of Biology, Westlake Institute for Advanced Study, Hangzhou, Zhejiang Province 310024, China.
Indole-3-acetic acid (IAA), the major form of auxin, is essential for plant growth. Auxin resistant 1 (AUX1), the first identified auxin importer, plays a crucial role in polar auxin transport (PAT). Here, we present cryo-EM structures of AUX1 in the IAA-free and IAA-bound states.
View Article and Find Full Text PDFPlants (Basel)
May 2025
Shanghai Key Laboratory of Protected Horticulture Technology, Horticultural Research Institute, Shanghai Academy of Agricultural Science, Shanghai 201403, China.
The auxin efflux transporter PIN protein plays a crucial role in the asymmetric distribution of auxin on the plasma membrane, influencing the growth and development of plant organs. In this study, we identified nine members of the gene family in the cucumber genome, which could be classified into five phylogenetic groups. These genes have diverse structures but conserved transmembrane domains.
View Article and Find Full Text PDFCold Spring Harb Protoc
March 2025
Department of Biology, Whitman College, Walla Walla, Washington 99362, USA
The AuxInYeast system is a synthetic biology tool that facilitates complex biochemical analysis of the plant auxin hormone signaling pathway. As a plant synthetic biology chassis, yeast offers rapid growth, well-established genetic and biochemical tools, and core eukaryotic cellular machinery compatible with heterologous plant gene expression. The AuxInYeast system for maize consists of yeast cells containing the minimal necessary set of plant auxin signaling parts: a receptor (ZmTIR1/AFB), repressor (ZmIAA), corepressor (REL2), transcription factor (ZmARF), and auxin response -element (auxRE).
View Article and Find Full Text PDFStructure
February 2025
Department of Molecular and Cell Biology, University of California at Berkeley, Berkeley, CA 94720, USA. Electronic address:
In a recent issue of Nature, Bayly-Jones et al. report the first cryoelectron microscopy (cryo-EM) structure of the lysosomal transmembrane protein LYCHOS, which mediates cholesterol sensing by mTORC1. LYCHOS forms a homodimer, with cholesterol engagement at the transporter-GPCR domain interface, coupled to auxin binding at the transporter-like domain, suggesting multi-domain coordination as critical for cholesterol sensing.
View Article and Find Full Text PDFTrends Plant Sci
November 2024
College of General Education, Kookmin University, Seoul 02707, South Korea. Electronic address:
Auxin is a key phytohormone, but the mechanism underlying apoplastic auxin perception has remained elusive. Yu et al. recently demonstrated that the interaction of two novel apoplast-localized auxin-binding protein 1 (ABP1)-like proteins, ABL1 and ABL2, with transmembrane kinases (TMKs) shapes extracellular auxin perception in both an overlapping and an ABP1-independent manner.
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