Proteome-Wide Identification of Non-histone Lysine Methylation during Grape Berry Ripening

To gain a comprehensive understanding of non-histone
methylation
during berry ripening in grape (Vitis vinifera L.), the methylation of non-histone lysine residues was studied
using a 4D label-free quantitative proteomics approach. In total,
822 methylation sites in 416 methylated proteins were identified,
with xxExxx_K_xxxxxx as the conserved motif. Functional annotation
of non-histone proteins with methylated lysine residues indicated
that these proteins were mostly associated with “ripening and
senescence”, “energy metabolism”, “oxidation–reduction
process”, and “stimulus response”. Most of the
genes encoding proteins subjected to methylation during grape berry
ripening showed a significant increase in expression during maturation
at least at one developmental stage. The correlation of methylated
proteins with QTLs, SNPs, and selective regions associated with fruit
quality and development was also investigated. This study reports
the first proteomic analysis of non-histone lysine methylation in
grape berry and indicates that non-histone methylation plays an important
role in grape berry ripening.