Mechanical Deformation Accelerates Protein Ageing

Abstract

A hallmark of tissue ageing is the irreversible oxidative modification of its proteins. We show that single proteins, kept unfolded and extended by a mechanical force, undergo accelerated ageing in times scales of minutes to days. A protein forced to be continuously unfolded completely loses its ability to contract by folding, becoming a labile polymer. Ageing rates vary among different proteins, but in all cases they lose their mechanical integrity. Random oxidative modification of cryptic side chains exposed by mechanical unfolding can be slowed by the addition of antioxidants such as ascorbic acid, or accelerated by oxidants. By contrast, proteins kept in the folded state and probed over week‐long experiments show greatly reduced rates of ageing. We demonstrate a novel approach whereby protein ageing can be greatly accelerated: the constant unfolding of a protein for hours to days is equivalent to decades of exposure to free radicals under physiological conditions.

The Work of Titin Protein Folding as a Major Driver in Muscle Contraction

“…This revealed a mechanical hierarchy within the Ig domains, with proximal Ig domains (nearer to the N-terminal) having lower mechanical stability than the distal Ig domains of the I-band. Further engineering of a covalent HaloTag anchor to either the N- or C-terminus of the protein has permitted specific immobilization of recombinant titin proteins for study at high force and long durations (41, 49, 57). …”

From Synthesis of Amino Acids and Peptides to Enzymatic Catalysis: A Bottom‐Up Approach in Mechanochemistry

“…Direct evidence of mechanical deformation with accelerated protein ageing was recently reported by Valle-Orero et al [45] Subjecting proteins to repeated folding and unfolding was found to reduce the ability of the protein to return to the orig-inal conformation.E xtrapolating these results to enzyme chemistry meanst hat denaturation could easily occur when exposing biocatalysts to harshm echanical conditions such as the ones experienced in ball mills. An enhancement of the enzymes tabilityw as achieved through immobilization of the biocatalysts on variouss upports.…”

Protein nanomechanics in biological context

“…The rich interplay between protein biochemistry and nanomechanics is also exemplified by the mechanical effects of disulfide isomerization, which can be trigged by mechanical force resulting in force-dependent nanomechanical modulation (Alegre-Cebollada et al 2011b ; Giganti et al 2018 ). Intriguingly, extended polypeptides age in a time scale of minutes to days losing their ability to fold (Valle-Orero et al 2017b ). Although the mechanisms behind this observation are not completely understood, it is possible that accumulating chemical modifications could contribute to the inability of the protein to refold, similar to the effects of S-glutathionylation described above.…”