RXLR effector PexRD54 couples host cellular transport components to autophagic compartments to stimulate autophagosome biogenesis and haustorial transport

YASIN DAGDAS; CIAN DUGGAN; TOLGA BOZKURT; POOJA PANDEY; ALEXIA TOUFEXI; SOPHIEN KAMOUN; BAYANTES DAGVADORJ; MARÍA EUGENIA SEGRETIN

Portland

Congreso; 2016 ISMPMI XVII Congress; 2016

International Society for Molecular Plant Microbe Interactions

A selective form of autophagy organized by autophagy cargo receptors contributes to immunity in plants and animals.However, we know little about how it is regulated and contributes to immunity at the molecular level. We discovered thatPhytophthora infestans effector PexRD54 stimulates autophagosome formation and subverts host defenses mediated byplant autophagy cargo receptor Joka2 by outcompeting it for binding the host autophagy regulator ATG8CL. Here weinvestigated the mechanisms underlying PexRD54 triggered autophagosome biogenesis, cargo sorting and transport. Wediscovered that PexRD54 stimulates autophagosome formation by coupling host vesicle transport regulators to ATG8CLcoatedautophagosomes. PexRD54 interacted with the GDP bound form of the host Rab GTPase Rab8 through its Nterminal WY motifs, whereas it bound ATG8CL via a short C terminal motif. However, ATG8CL colocalized and interactedwith Rab8 in the presence of PexRD54. Conversely, Rab8 did not associate with Joka2 indicating that the content ofautophagic cargo recruited by PexRD54 and Joka2 are different. Furthermore, genetic interference of Rab8 activity orimpairment of its interaction with PexRD54 lead to reduced autophagosome formation. Finally, PexRD54labeledautophagosomes are diverted towards haustoria, possibly to allocate cellular resources. Our results implicate effectormediatedemployment of a Rab GTPase in autophagosome biogenesis and show that effectors can serve as adaptorstargeting protein complexes to coopthost processes.