%0 Journal Article %A Ooi-Kock Teh %A Chil-Woo Lee %A Franck Aniset Ditengou %A Till Klecker %A Giulia Furlan %A Marco Zietz %A Gerd Hause %A Lennart Eschen-Lippold %A Wolfgang Hoehenwarter %A Justin Lee %A Thomas Ott %A Marco Trujillo %T Phosphorylation of the exocyst subunit Exo70B2 contributes to the regulation of its function %D 2018 %R 10.1101/266171 %J bioRxiv %P 266171 %X The exocyst is a conserved hetero-octameric complex mediating early tethering during exocytosis. Its Exo70 subunit plays a critical role as a spatiotemporal regulator by mediating numerous protein and lipid interactions. However, a molecular understanding of the exocyst function remains challenging. We show that Exo70B2 locates to dynamic foci at the plasma membrane and transits through a BFA-sensitive compartment, reflecting its canonical function in secretion. However, treatment with the salicylic acid (SA) defence hormone analogue Benzothiadiazole (BTH), or the immunogenic peptide flg22, induced Exo70B2 transport into the vacuole. We uncovered two ATG8- interacting motifs (AIMs) located in the C-terminal domain (C-domain) that mediate its recruitment into the vacuole. Moreover, we also show that Exo70B2 is phosphorylated near the AIMs and mimicking phosphorylation enhanced ATG8 interaction. Finally, Exo70B2 phosphonull lines were hypersensitive to BTH and more resistant to avirulent bacteria which induce SA production. Our results suggest a molecular mechanism in which phosphorylation of Exo70B2 by MPK3 functions in a feed-back system linking cellular signalling to the secretory pathway. %U https://www.biorxiv.org/content/biorxiv/early/2018/02/19/266171.full.pdf