ESCRT-I Component VPS23A Affects ABA Signaling by Recognizing ABA Receptors for Endosomal Degradation

Abstract

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Proteasome‐independent functions of lysine‐63 polyubiquitination in plants

“…The ELC/AtVPS23A ESCRT-I component also binds Ub in vitro (Spitzer et al, 2006). Interestingly, ELC/ AtVPS23A and AtFYVE1 directly bind to the AtPYL4 abscisic acid (ABA) receptor and AtIRT1, two ubiquitinated endocytosed cargos (Barberon et al, 2014;Belda-Palazon et al, 2016;Yu et al, 2016). Consistently, genetic interference with ELC/AtVPS23A or AtFYVE1 expression yields ubiquitinated protein accumulation in (Zhou et al, 2013), sequestration of anthocyanins in the vacuole (Pourcel et al, 2010), chlorophagy of physiological and damaged chloroplasts (Izumi et al, 2017), reticulophagy (Liu et al, 2012), pexophagy (Shibata et al, 2013), mitophagy (Li et al, 2014) and xenophagy (Hafren et al, 2017).…”

“…A limited number of integral or associated plasma membrane proteins are known to be ubiquitinated in vivo, carrying either multi-monoUb and/or K63-linked chains (Barberon et al, 2011;Kasai et al, 2011;Roberts et al, 2011;Leitner et al, 2012;Lin et al, 2013;Bueso et al, 2014;Yu et al, 2016). The use of a K63 polyUb-specific sensor coupled to proteomics greatly enhanced the repertoire of plasma membrane proteins conjugated with K63-linked chains (Johnson & Vert, 2016).…”

“…The BR receptor AtBRI1 is indeed decorated with K63-linked chains in vivo, undergoes K63 polyUb-dependent New Phytologist endocytosis and the expression of a ubiquitination-defective BRI1 variant leads to BR hypersensitivity (Martins et al, 2015). Similarly, the plasma membrane-associated pool of AtPYR/AtPYL ABA receptors is subjected to ubiquitination at the plasma membrane by the AtRSL1 RING E3 ligase and ESCRT-dependent endocytic sorting (Bueso et al, 2014;Belda-Palazon et al, 2016;Yu et al, 2016). Consistently, Arabidopsis fyve1 and vps23 mutants show stabilization of the AtPYL4 ABA receptor and are hypersensitive to ABA.…”

A novel family of transcription factors conserved in angiosperms is required for ABA signalling

“…So far, two main types of negative feedback regulatory loops of ABA signalling have been identified: the ubiquitin‐mediated proteasomal degradation of ABA key central regulators and the expressional regulation of the key central regulators genes. E3 ligases such as KEG, DWA1, and DWA2 target ABF/AREB/ABI5‐type bZIP transcription factors for proteasomal degradation (Chen, Liu, Stone, & Callis, ; Lee, Kang, et al, ; Liu & Stone, , ; Stone, Williams, Farmer, Vierstra, & Callis, ), whereas E2 ligase VPS23A and E3 ligases CUL4 and RSL1 promote the proteasomal degradation of PYR/PYL/RCABR receptors (Belda‐Palazon et al, ; Bueso et al, ; Seo et al, ; Yu et al, ). E3 ligases PUB12 and PUB13 target PP2C proteins, but only when they interact with ABA receptors (Kong et al, ).…”

ESCRT‐dependent vacuolar sorting and degradation of the auxin biosynthetic enzyme YUC1 flavin monooxygenase

“…Membrane‐localized auxin efflux carrier PIN2 (Spitzer et al ) and Brassinosteroid receptor BRI1 (Martins et al ) have been reported to be PVC cargo proteins, and are sorted for vacuolar degradation by the ESCRT system. Although the ESCRT pathway has long been considered specifically to be targeting integral membrane proteins, recent studies have demonstrated that non‐integral membrane proteins, such as the Arabidopsis ABA receptor PYR1‐LIKE 4 (PYL4), also employ ESCRT machinery components FYVE1 and VPS23A for endosomal sorting (Belda‐Palazon et al ; Yu et al ).…”