Proteomics unveils chemical modifications on protein side chains in raw breast meat of broilers (Gallus gallus) affected with growth-related myopathies.

OBJECTIVE: This study aimed to investigate how growth-related myopathies influenced chemical modifications formed on amino acid residues of chicken breast proteins. METHODS: Breasts (pectoralis major) of commercial broilers (Gallus gallus) were classified into "normal", White Striping (WS)" and "White Striping + Wooden Breast (WS+WB)" groups (n = 9 per group). The meat was subjected to proteomic analysis using a liquid chromatography-tandem mass spectrometry. Differences in abundance of modified sites, including methylated lysine (Lys) and arginine, acetsylated Lys, and oxidized methionine (Met), due to the growth-related myopathies were identified (false discovery rate [FDR]<0.05). Biological functions of the proteins were analyzed. RESULTS: Proteomics revealed 185, 105, and 194 modified sites for methylation, Lys acetylation and Met oxidation, respectively. Of 185, 10 sites from seven proteins (TPM1, MYH, MYH1F, DICER1, RCJMB04_5k17, TPI1, and VIM) showed differential abundance in the methylation (FDR<0.05). Seven acetylated Lys sites from five proteins (TPM1, ADHFE1, SPAG9, PCNT, and RCJMB04_5k17) were differentially expressed. The abundance of those sites in normal samples were lower than those of WS samples (FDR<0.05). As for oxidized Met, differential 62 sites were identified (FDR<0.05). The major Met-oxidized protein was MYH. Met oxidation of 40 sites from 22 proteins was increased in WS samples whereas 19 sites of four proteins (MYL11, MYH, MYH1F, and TNNT2) were increased in WS+WB samples. Only four sites from DICER1, LDHA and LDB3 were found in normal samples (FDR<0.05). CONCLUSION: The findings shed light on the links between oxidative stress and oxidized Met in the chicken with growth-related myopathies. In addition, methylation and acetylation modifications likely played a role in dynamic cell signaling to maintain cellular activities, particularly metabolism and energy production, against the stress in the affected birds.