Abstract
Protein lysine 2-hydroxyisobutyrylation (Khib), a new type of post-translational modification, occurs in histones and non-histone proteins and plays an important role in almost all aspects of both eukaryotic and prokaryotic living cells. Fusarium oxysporum, a soil-borne fungal pathogen, can cause disease in more than 150 plants. However, little is currently known about the functions of Khib in this plant pathogenic fungus. Here, we report a systematic analysis of 2-hydroxyisobutyrylated proteins in F. oxysporum. In this study, 3782 Khib sites in 1299 proteins were identified in F. oxysporum. The bioinformatics analysis showed that 2-hydroxyisobutyrylated proteins are involved in different biological processes and functions and are located in diverse subcellular localizations. The enrichment analysis revealed that Khib participates in a variety of pathways, including the ribosome, oxidative phosphorylation, and proteasome pathways. The protein interaction network analysis showed that 2-hydroxyisobutyrylated protein complexes are involved in diverse interactions. Notably, several 2-hydroxyisobutyrylated proteins, including three kinds of protein kinases, were involved in the virulence or conidiation of F. oxysporum, suggesting that Khib plays regulatory roles in pathogenesis. Moreover, our study shows that there are different Khib levels of F. oxysporum in conidial and mycelial stages. These findings provide evidence of Khib in F. oxysporum, an important filamentous plant pathogenic fungus, and serve as a resource for further exploration of the potential functions of Khib in Fusarium species and other filamentous pathogenic fungi.
Highlights
Post-translational modifications (PTMs) of proteins play key roles in diverse biological processes of cells and are dynamic and reversible modification reactions occurring during or after biosynthesis, including amino acid synthesis, protein interaction networks, and energy metabolism (Zhou et al, 2016; Liu et al, 2018a)
We found that 43.6% of the 2-hydroxyisobutyrylated proteins have only one 2-hydroxyisobutyrylated site and that 56.4% of them contain two or more modified sites
The enrichment analysis of the protein domain demonstrated that the proteasome subunit, RNA polymerase Rpb2, elongation factor Tu GTP-binding and LSM domains were all enriched and tended to be 2-hydroxyisobutyrylated in F. oxysporum proteins (Figure 5B and Supplementary Table 11). These results showed that 2-hydroxyisobutyrylated proteins are widely distributed in cells and associated with diverse pathways, suggesting that Khib plays an important role in cell metabolism and amino acid biosynthesis
Summary
Post-translational modifications (PTMs) of proteins play key roles in diverse biological processes of cells and are dynamic and reversible modification reactions occurring during or after biosynthesis, including amino acid synthesis, protein interaction networks, and energy metabolism (Zhou et al, 2016; Liu et al, 2018a). Lysine 2-hydroxyisobutyrylation (Khib), a type of lysine modification, was discovered in histones and is conserved from yeast to humans (Dai et al, 2014; Huang et al, 2017, 2018). Khib was identified as a new histone mark in eukaryotic cells, and 63 Khib sites on histone proteins have been identified by MS analysis and biochemical methods in humans and mice (Dai et al, 2014; Cheng et al, 2020). A systematic analysis of Khib sites in P. patens histone proteins demonstrated some conserved sites in histone H3 and H4 proteins and revealed unknown sites in histone H1, H2A, and H2B proteins (Vidali and Bezanilla, 2012; Yu et al, 2017)
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