Arabidopsis AGO1 N-terminal Poly-Q domain promotes phase separation and association with stress granules during heat stress

ABSTRACT: In Arabidopsis thaliana, ARGONAUTE1 (AGO1) plays a central role in microRNA (miRNA) and small interfering RNA (siRNA)-mediated silencing. Nuclear AGO1 is loaded with miRNAs and exported to the cytosol where it associates to the rough ER to conduct miRNA-mediated translational repression, mRNA cleavage and biogenesis of phased siRNAs. These latter, as well as other cytosolic siRNAs, are loaded into cytosolic AGO1, but in which compartment this happens is not known. Moreover, the effect of stress on AGO1 localization is still unclear. Here, we show that heat stress (HS) promotes AGO1 protein accumulation, which co-localize with components of the siRNA bodies and of stress granules (SGs). AGO1 does not need SGS3, a key component of siRNA bodies, to efficiently form condensates during HS. Instead, we found that the still poorly characterized N-terminal Poly-Q domain of AGO1, which contains a prion-like domain, is sufficient to undergo phase separation. Moreover, an exposure of 1 hour to HS only moderately affected AGO1 loading by miRNAs and target cleavage, suggesting that its localization in condensates protects AGO1 rather than promote its activity in reprograming gene expressing during stress. Collectively, our work shed new light on the impact of high temperature on a main effector of RNA silencing in plants.

INSTRUMENT(S): Q Exactive Plus

ORGANISM(S): Arabidopsis Thaliana (mouse-ear Cress)

TISSUE(S): Seedling

SUBMITTER: Johana Chicher  

LAB HEAD: Pascal Genschik

PROVIDER: PXD048594 | Pride | 2024-06-22

REPOSITORIES: Pride