UBA domain protein SUF1 interacts with NatA-complex subunit NAA15 to regulate thermotolerance in Arabidopsis

During recovery from heat stress,plants clear away the heat-stress-induced misfolded proteins through the ubiquitin-proteasome system(UPS).In the UPS,the recognition of substrate proteins by E3 ligase can be regulated by the N-terminal acetyltransferase A(NatA)complex.Here,we determined that Arabidopsis STRESS-RELATED UBIQUITIN-ASSOCIATED-DOMAIN PROTEIN FACTOR 1(SUF1)interacts with the NatA complex core subunit NAA15 and positively regulates NAA15.The suf1 and naa15 mutants are sensitive to heat stress;the NatA substrate NSNC1 is stabilized in suf1 mutant plants during heat stress recovery.Therefore,SUF1 and its interactor NAA15 play important roles in basal thermotolerance in Arabidopsis.