Validamycin A Enhances the Interaction Between Neutral Trehalase and 14-3-3 Protein Bmh1 in Fusarium graminearum

Abstract

Trehalase is considered the main target of the biological fungicide validamycin A, and toxicology mechanism of validamycin A is unknown. 14-3-3 proteins, highly conserved proteins, participate in diverse cellular processes, including enzyme activation, protein localization and molecular chaperone. In Saccharomyces cerevisiae, the 14-3-3 protein Bmh1could interact with Nth1 to respond specific external stimuli. Here, we characterized FgNth, FgBmh1, and FgBmh2 in Fusarium graminearum. ΔFgNth, ΔFgBmh1, and ΔFgBmh2 displayed great growth defects when compared to wild-type PH-1. When exposed to validamycin A, high osmotic and high temperature stresses, ΔFgNth, ΔFgBmh1, and ΔFgBmh2 showed more tolerance than WT. Both ΔFgNth and ΔFgBmh1 displayed reduced deoxynivalenol (DON) production but opposite for ΔFgBmh2, and all three deletion mutants showed reduced virulence on wheat coleoptiles. In addition, Co-immunoprecipitation (Co-IP) experiments suggested that FgBmh1 and FgBmh2 both interact with FgNth, but no interaction was detected between FgBmh1 and FgBmh2 in our experiments. Further, validamycin A enhances the interaction between FgBmh1 and FgNth in a positive correlation under concentrations of 1-100μg/mL. Besides, both high osmotic and high temperature stresses promote the interaction between FgBmh1 and FgNth. Co-IP assay also showed that neither FgBmh1 nor FgBmh2 could interact with FgPbs2, a MAPKK kinase in the high-osmolarity glycerol (HOG) pathway. However, FgBmh2 but not FgBmh1 binds to the heat shock protein FgHsp70 in F. graminearum. Taken together, our results demonstrate that FgNth and FgBmhs are involved in growth, responces to external stresses and virulence, and validamycin A enhanced the interaction between FgNth and FgBmh1in F. graminearum.

Trehalase Inhibitor Validamycin May Have Additional Mechanisms of Toxicology against Rhizoctonia cerealis

“…Recent studies have shown that validamycin inhibits deoxynivalenol (DON) biosynthesis by targeting the neutral trehalase from F. graminearum and reducing the interaction between neutral trehalase and pyruvate kinase, a key enzyme in glycolysis; furthermore, validamycin synergizes with demethylation inhibitor (DMI) fungicides against F. graminearum by decreasing sterol 14α-demethylase enzyme (CYP51s) expression [ 17 , 18 , 19 , 20 ]. In this study, we demonstrated that validamycin obviously inhibited the mycelium growth of R. cerealis on PDA plates at a concentration of 0.…”

“…Validamycin A (60%) (Qianjiang Biochemical, Haining, China) was dissolved in sterile water. Growth tests were performed on PDA [ 20 ]. The culture medium for different carbon conditions was prepared by substituting glucose in the PDA medium with trehalose (PTA) to obtain media with the same carbon content (2% w/v ) and different carbon sources.…”

“…(ascomycetes), in wheat is not ideal [ 17 ]. However, recent research has shown that validamycin can be combined with DMI fungicides to reduce Fusarium mycotoxins production and prevent FHB [ 17 , 18 , 19 , 20 ]. However, the toxicology mechanisms of validamycin in fungi are unclear.…”

The yeast 14-3-3 proteins Bmh1 and Bmh2 regulate key signaling pathways

“…In the plant pathogen Fusarium graminearum , the interaction between Nth1 and Bmh1 is enhanced by validamycin A, albeit through an unclear mechanism ( Ren et al, 2022 ). Nevertheless, Nth1 activation by Bmh proteins is a classic example of a mode of action whereby 14-3-3 proteins modulate the enzymatic activity of the bound protein by changing the structure of its active site ( Obsilova et al, 2014 ).…”