STA regulates succinylated AflM triggered by SCS to contribute to aflatoxin biosynthesis through the Ach1

<i>Aspergillus flavus</i> and its secondary metabolites, aflatoxins (AFs), especially aflatoxin B1 (AFB1), seriously affect agricultural production, food storage, and human health. Succinyl-CoA synthase ADP-forming subunit β (SCS) is involved in the synthesis of succinate from succinyl-CoA in the tricarboxylic acid cycle. In this study, we demonstrated that SCS led to decreased aflatoxin production. Bioassay results showed that deletion of <i>sucB</i> (the gene coding for SCS) led to increased succinyl-CoA accumulation. Catalyzed by succinyl transferase (STA), the increased amount of succinyl-CoA in Δ<i>sucB</i> leads to increased levels of global protein succinylation, which causes upregulation of AFB1 accumulation in Δ<i>sucB</i>. To elucidate the mechanism of increased AFB1 accumulation in Δ<i>sucB</i>, the relevant enzymes and metabolites involved in the aflatoxin biosynthesis pathway were examined through proteome and metabolome analyses. These data illustrate that the deletion of <i>sucB</i> results in an increase in (1’S, 5’S) – averufin catalyzed by AflK, (1’S)-averantin catalyzed by AflD, and aflatoxin G2/O- methylsterigmatocystin catalyzed by AflP. We also found that AflM is not only upregulated but also succinylated in Δ<i>sucB</i>; Ach1 (acetyl-CoA hydrolase, Ach1) is downregulated in Δ<i>sucB</i> and interacts with SCS. Therefore, we deduce a pathway of Ach1/STA-SCS-succinylated AflM for AFB1 biosynthesis, which provides knowledge for the control of <i>A. flavus</i> and AFs.