Spontaneous Post-translational Modification: Crosstalk of Proteolysis, Autophagy, and Apoptosis in Aging

Biochirality is evident in the hierarchical relation of molecular and cellular physiology during organism development and aging. Chirality influences the higher levels of biological processes, such as perception, memory and cognition, through intermolecular interactions between DNA, proteins, and lipids. At the molecular level, an organism's aging is the accumulation of macro-molecules with the aberrant composition, chirality, and folding. Cellular aging is driven by the non-physiological phase transitions (PhTs) withing membrane-bound and membrane-less compartments. Genomic instability and protein aging, as the interconnected root-causes of cell and organism aging, share two essential feature – spontaneous nature and accumulation over a lifetime. Consequently, we will analyze the interaction between the enzymatic (Enz) and spontaneous (Sp) post-translational modifications (PTMs^Enz and PTMs ^Sp). Both forms of PTMs significantly contribute to the balance of L- and D-amino acids (L/D-AAs) in organisms, modulating the functions of nervous and immune systems. The most abundant form of PTM - enzymatic phosphorylation is bio-chemically associated with the spontaneous racemization (Rz^Sp). The crass talk of enzymatic phosphorylation and spontaneous racemization, as an essential determinant of protein aging and aggregation, associated with the aberrant autophagy, apoptosis, and cell signaling, is discussed in this review.