Fig. 7: Hsp83 acetylation stabilizes the co-chaperone complex to regulate protein homeostasis.

a, b, Y2H (a) and Split luciferase assay (b) showing Sti1 is a co-chaperone between Hsp83 and Hsp70. c Competitive Hsp83 co-IP data indicating that the acetylation of Hsp83 K381 and K410 residues affects its binding affinity to Sti1. The co-immunoprecipitated Sti1-GFP and Hsp70 were detected using anti-GFP and anti-Hsp70 antibodies, respectively. The experiment was repeated three times and showed similar results. d TG1-2cf, surfactin treatments, and VdArd1 deletion reduce Hsp83 binding affinity to Sti1 and Hsp70. Competitive Hsp83 co-IP was performed in Sti1-GFP/Hsp83-Flag strains expressing VdArd1 (V592)/not expressing VdArd1 (VdΔard1), or treated with TG1-2cf or surfactin. The experiment was repeated three times and showed similar results. e Immunoblotting results showing the effect of TG1-2cf and surfactin treatments, and K381/410 R, K381/410Q mutations, and VdArd1 dysfunction on the overall protein ubiquitination levels in V. dahliae. Overall protein ubiquitination was assessed using anti-ub antibody. The experiment was repeated three times and showed similar results. f A proposed model of NatA acetyltransferase complex-medicated acetylation in V. dahliae tolerance to beneficial bacterium TG1-2. The NatA acetyltransferase complex acetylates Hsp83 at K381 and K410 sites, enabling Hsp83 to bind to the co-chaperone Sti1 and mediate protein refolding in V. dahliae, thereby antagonizing TG1-2-induced apoptosis. In turn, the anti-microbial compound produced by TG1-2 can target the NatA complex, resulting in reduced acetylation of Hsp83 and increased protein ubiquitination, thereby resulting in enhanced protein degradation and cell apoptosis. Source data are provided as a Source Data file. Figure created in BioRender. Duan, C. (2025) https://biorender.com/743qc1y.