44 / 2019-12-04 11:22:11

Quantitative proteomics for studying the effect of lysine succinylation on aflatoxin production in Aspergillus flavus

Quantitative proteomics；aflatoxin production ；Aspergillus flavus

Aflatoxins (AFs) are mainly produced by Aspergillus flavus, which is one of important factors causing hepatocellular carcinoma in developing countries [1]. The biosynthesis of aflatoxin has been well studied. However, there are very few studies reported on the influence of post-translational modification (PTM) on aflatoxin. Lysine succinylation was firstly found to act as a protein PTM pathway in 2011, and this modification widely existed in both eukaryotic and prokaryotic cells [2]. Lysine-succinylated proteins are widely found in mitochondrial enzymes which are predominantly involved in fatty acid metabolism, amino acid degradation and the tricarboxylic acid (TCA) cycle [3]. In order to study the relationship between lysine succinylation and aflatoxin production, the proteomic quantification of lysine succinylation was performed using TMT labeling and Ksucc affinity enrichment followed by high-resolution LC-MS/MS analysis, then quantitative lysine succinylome analysis was performed in a pair of cell lines between high-yield and low-yield aflatoxin in Aspergillus flavus. In total, 1,240 lysine succinylation sites in 768 proteins were identified, among which 1,103 lysine succinylation sites in 685 proteins were quantified. The difference was deemed significant when proteins with quantitative ratios above 1.5 or below 0.667. Therefore, the two ratios were selected as the defining values of up-regulation and down-regulation of proteins. Among the quantified proteins, 8 lysine succinylation sites in 8 proteins were up-regulated and 502 lysine succinylation sites in 360 proteins were down-regulated as compared with the control sample. Intensive bioinformatics analyses were then carried out to annotate those quantifiable lysine succinylated targets. The results of gene ontology annotation and KEGG pathway analysis show that these succinylated are mostly related to carbon metabolic process. Further, we found that succinylation of K135 in VBS protein might be related to aflatoxin production through mapping these succinalated proteins with aflatoxin biosynthesis. This study provides novel insights into the functions of succinylation in the regulation of aflatoxin production in Aspergillus flavus.