Selective autophagy regulates heat stress memory by NBR1-mediated targeting of HSP90 and ROF1

ABSTRACT: In nature, plants are constantly exposed to many transient, but recurring, stresses. Thus, to complete their life cycles they require a dynamic balance between capacities to recover following cessation of stress and maintenance of stress memory. Recently, we uncovered a new functional role of autophagy in regulating recovery from heat stress (HS) and resetting cellular memory of HS in Arabidopsis thaliana. Here, we demonstrate that NBR1 (Next-to-BRCA1) plays a crucial role as an adaptor receptor for selective autophagy during recovery from HS. Immunoblot analysis and confocal microscopy revealed that levels of NBR1 protein, NBR1-labeled puncta and NBR1 activities were all higher during the HS recovery phase than before and after this phase. Co-immunoprecipitation analysis of proteins interacting with NBR1 and comparative proteomic analysis of a nbr1 knockout mutant and wild-type plants identified 58 proteins as potential novel targets of NBR1. Cellular, biochemical and functional genetic studies confirmed that NBR1 targets Heat Shock Protein 90 (HSP90) and ROF1, a member of the FKBP family, and mediates their degradation by autophagy, which represses the expression of HSPs regulated by HsfA2 transcription factor and the response to HS. Accordingly, loss-of-function mutation of NBR1 resulted in a stronger HS memory phenotype. Together our results provide new insights into the mechanistic principles by which autophagy regulates plant response to recurrent HS.

INSTRUMENT(S): Q Exactive

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

TISSUE(S): Rosette

SUBMITTER: Michal Gorka  

LAB HEAD: Salma Balazadeh

PROVIDER: PXD015027 | Pride | 2022-02-15

REPOSITORIES: Pride