ERC1 proteins are shown to develop into ring-like upon autophagic induction.
ERC1 proteins interact with ATG8 and translocate to the phagophore membrane during autophagy.
They can assemble into large droplets with ATG8e proteins before ATG8 binds to the membrane.
ERC1 represents a unique type of plant condensate that plays a role in autophagy.
ERC1 directly interacts with NBR1, facilitating its degradation.
Dysfunction of ERC1 leads to reduced turnover of ubiquitinated proteins and decreased heat stress tolerance in plants.
Simplified
Macroautophagy (hereafter autophagy) is essential for cells to respond to nutrient deficiency by delivering cytosolic contents to vacuoles for degradation via the formation of a multilayer organelle named an . A set of autophagy-related (ATG) regulators are recruited to the phagophore assembly site for phagophore initiation, including its expansion and closure, and subsequent delivery into the vacuole. However, it remains elusive how the phagophore assembly is regulated under different stress conditions. Here, we described an uncharacterized() ERC (ELKS/Rab6-interacting/CAST) protein family as an interacting partner of ATG8. ERC1 proteins translocate to the phagophore membrane and develop into ring-like autophagosomes upon autophagic induction. Notably, we found that ERC1 proteins possess the ability to assemble into substantial droplets together with ATG8e proteins prior to ATG8 conjugation to the membrane. Through multiscale characterization, we demonstrated that the ERC1 membraneless droplet represents a distinct type of plant condensate. Additionally, ERC1 directly binds to NBR1 to promote NBR1 degradation. ERC1 dysfunction suppresses the turnover of ubiquitinated substrates and compromises plant tolerance to heat stress. Our study suggests a model for autophagic degradation in response to heat stress by the action of ERC1-mediated in. Arabidopsis Arabidopsis thaliana Arabidopsis
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