ABP1 Mediates Auxin Inhibition of Clathrin-Dependent Endocytosis in Arabidopsis

Abstract

Summary Spatial distribution of the plant hormone auxin regulates multiple aspects of plant development. These self-regulating auxin gradients are established by the action of PIN auxin transporters, whose activity is regulated by their constitutive cycling between the plasma membrane and endosomes. Here, we show that auxin signaling by the auxin receptor AUXIN-BINDING PROTEIN 1 (ABP1) inhibits the clathrin-mediated internalization of PIN proteins. ABP1 acts as a positive factor in clathrin recruitment to the plasma membrane, thereby promoting endocytosis. Auxin binding to ABP1 interferes with this action and leads tothe inhibition of clathrin-mediated endocytosis. Our study demonstrates that ABP1 mediates a nontranscriptional auxin signaling that regulates the evolutionarily conserved process of clathrin-mediated endocytosis and suggests that this signaling may be essential for the developmentally important feedback of auxin on its own transport.

Auxin-Binding Protein 1 is a negative regulator of the SCFTIR1/AFB pathway

“…Even more interestingly, this data is opposite to the one resulting from ABP1 inactivation (Fig. 3), whereas both endocytosis inhibitors and ABP1 inactivation impair endocytosis clathrin-dependent 13,32 . It clearly indicates that in no way at all the enhanced degradation of AUX/IAA after functional inactivation of ABP1 is originated from endocytosis inhibition.…”

“…In addition to TIR1/AFB-AUX/IAA coreceptors, auxin is also perceived by ABP1 that is associated with the plasma membrane and was shown to be involved in the regulation of ion fluxes at the plasma membrane 10 and, more recently, in the activation of ROP GTPases 11,12 in response to auxin. ABP1 was also shown to be essential for clathrindependent endocytosis, acting as a positive factor for clathrin recruitment to the plasma membrane and inhibiting this process after binding to auxin 11,13 . The contribution of these early and potentially transient responses to growth and development is however still unknown.…”

“…And fifth, ABP1 was shown to be required for clathrin-dependent protein internalization and to reduce PIN protein recycling at the plasma membrane 11,13 . In consequence, ABP1 inactivation results in endocytosis inhibition, however, without affecting polar localization of PIN auxin efflux proteins 13,16 and efficient efflux of auxin was shown to be maintained in roots 16 . More functional PIN efflux carriers at the plasma membrane thus suggest an enhanced ability to transport auxin out of the cells and a predictable decrease in auxin intracellular content.…”

A comparison of the effects of 1,4-naphthoquinone and 2-hydroxy-1,4-naphthoquinone (lawsone) on indole-3-acetic acid (IAA)-induced growth of maize coleoptile cells

“…2002). ABP1 is involved in: regulation of the membrane potential and ion fluxes; elevation in cytosolic Ca 2+ concentration (Shishova and Lindberg 2010) and changes in the cytoskeleton (Nagawa et al 2012), in the vesicular trafficking (Robert et al 2010), in the cell division and expansion (Braun et al 2008).…”

Plasma membrane protein ubiquitylation and degradation as determinants of positional growth in plants

“…Specifically, PIN3 and PIN7 have been implicated in redirecting auxin flow in columella root cap cells for further transport via lateral root cap and epidermis cells into the root meristem transition zone. These carrier proteins exhibit rapid relocation to the lower side of root cap cells within only a few minutes after application of a gravistimulus, sufficient for establishment of a hormone concentration gradient in the very root tip (Friml et al 2002;Kleine-Vehn et al 2010).…”