Lysine 2-hydroxyisobutyrylation orchestrates cell development and aflatoxin biosynthesis in Aspergillus flavus

Lysine 2-hydroxyisobutyrylation (K-hib) is a recently identified post-translational modification (PTM) that regulates numerous cellular metabolic processes. In pathogenic microorganism, although glycolysis and fungal virulence are regulated by K-hib, its potential roles in fungi remain to be elusive. Our preliminary results showed that levels of K-hib fluctuate over time in Aspergillus flavus, which frequently contaminates crops and produces carcinogenic aflatoxins. However, the perception of K-hib function in A. flavus is limited, especially in mycotoxin-producing strains. Here, we performed a comprehensive analysis of K-hib in A. flavus, and 7156 K-hib sites were identified in 1473 proteins. Notably, we demonstrated that K-hib of AflM, a key enzyme in aflatoxin biosynthesis, affected conidia production and sclerotia formation. Furthermore, aflM deletion impaired aflatoxin biosynthesis, and more importantly, strains in which K-hib was mimicked by K to T mutation at K49, K179 and K180 sites showed reduced aflatoxin production compared with wild type and Delta aflM complementation strains. These results indicate that K-hib at these sites of AflM negatively regulates aflatoxin biosynthesis in A. flavus. In summary, our study revealed the potential roles of K-hib in A. flavus, and particularly shed light on a new way to regulate aflatoxin production via K-hib.