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Structure of the auxin exporter PIN1 in Arabidopsis thaliana in the NPA-bound state
Structural highlights
FunctionPINI_ARATH Acts as a component of the auxin efflux carrier. Seems to be involved in the basipetal auxin transport. Mediates the formation of auxin gradient which is required to ensure correct organogenesis. Coordinated polar localization of PIN1 is directly regulated by the vesicle trafficking process and apical-basal PIN1 polarity also depends on the phosphorylation of conserved serine residues by PID kinase. The ARF-GEF protein GNOM is required for the correct recycling of PIN1 between the plasma membrane and endosomal compartments.[1] [2] [3] Publication Abstract from PubMedPolar auxin transport is unique to plants and coordinates their growth and development(1,2). The PIN-FORMED (PIN) auxin transporters exhibit highly asymmetrical localizations at the plasma membrane and drive polar auxin transport(3,4); however, their structures and transport mechanisms remain largely unknown. Here, we report three inward-facing conformation structures of Arabidopsis thaliana PIN1: the apo state, bound to the natural auxin indole-3-acetic acid (IAA), and in complex with the polar auxin transport inhibitor N-1-naphthylphthalamic acid (NPA). The transmembrane domain of PIN1 shares a conserved NhaA fold(5). In the substrate-bound structure, IAA is coordinated by both hydrophobic stacking and hydrogen bonding. NPA competes with IAA for the same site at the intracellular pocket, but with a much higher affinity. These findings inform our understanding of the substrate recognition and transport mechanisms of PINs and set up a framework for future research on directional auxin transport, one of the most crucial processes underlying plant development. Structural insights into auxin recognition and efflux by Arabidopsis PIN1.,Yang Z, Xia J, Hong J, Zhang C, Wei H, Ying W, Sun C, Sun L, Mao Y, Gao Y, Tan S, Friml J, Li D, Liu X, Sun L Nature. 2022 Sep;609(7927):611-615. doi: 10.1038/s41586-022-05143-9. Epub 2022 , Aug 2. PMID:35917925[4] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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