Force-regulated chaperone activity of BiP/ERdj3 is opposite to their homologs DnaK/DnaJ.

Polypeptide chains experience mechanical tension while translocating through cellular tunnels, which are subsequently folded by molecular chaperones. However, interactions between tunnel-associated chaperones and these emerging polypeptides under force is not completely understood. Our investigation focused on mechanical chaperone activity of two tunnel-associated chaperones, BiP and ERdj3 both with and without mechanical constraints and comparing them with their cytoplasmic homologs: DnaK and DnaJ.

Pan-cancer analyses suggest kindlin-associated global mechanochemical alterations.

Kindlins serve as mechanosensitive adapters, transducing extracellular mechanical cues to intracellular biochemical signals and thus, their perturbations potentially lead to cancer progressions. Despite the kindlin involvement in tumor development, understanding their genetic and mechanochemical characteristics across different cancers remains elusive. Here, we thoroughly examined genetic alterations in kindlins across more than 10,000 patients with 33 cancer types.

Structurally different chemical chaperones show similar mechanical roles with independent molecular mechanisms.

Osmolytes are well known to protect the protein structure against different chemical and physical denaturants. Since their actions with protein surfaces are mechanistically complicated and context dependent, the underlying molecular mechanism is not fully understood. Here, we combined single-molecule magnetic tweezers and molecular dynamics (MD) simulation to explore the mechanical role of osmolytes from two different classes, trimethylamine -oxide (TMAO) and trehalose, as mechanical stabilizers of protein structure.

Elucidating the novel mechanisms of molecular chaperones by single-molecule technologies.

Molecular chaperones play central roles in sustaining protein homeostasis and preventing protein aggregation. Most studies of these systems have been performed in bulk, providing averaged measurements, though recent single-molecule approaches have provided an in-depth understanding of the molecular mechanisms of their activities and structural rearrangements during substrate recognition. Chaperone activities have been observed to be substrate specific, with some associated with ATP-dependent structural dynamics and others via interactions with co-chaperones.

Direct Observation of the Mechanical Role of Bacterial Chaperones in Protein Folding.

Protein folding under force is an integral source of generating mechanical energy in various cellular processes, ranging from protein translation to degradation. Although chaperones are well known to interact with proteins under mechanical force, how they respond to force and control cellular energetics remains unknown. To address this question, we introduce a real-time magnetic tweezer technology herein to mimic the physiological force environment on client proteins, keeping the chaperones unperturbed.

Connecting conformational stiffness of the protein with energy landscape by a single experiment.

The structure-function dynamics of a protein as a flexible polymer is essential to describe its biological functions. Here, using single-molecule magnetic tweezers, we have studied the effect of ionic strength on the folding mechanics of protein L, and probed its folding-associated physical properties by re-measuring the same protein in a range of ammonium sulfate concentrations from 150 mM to 650 mM. We observed an electrolyte-dependent conformational dynamics and folding landscape of the protein in a single experiment.

Integrin Regulated Autoimmune Disorders: Understanding the Role of Mechanical Force in Autoimmunity.

The pathophysiology of autoimmune disorders is multifactorial, where immune cell migration, adhesion, and lymphocyte activation play crucial roles in its progression. These immune processes are majorly regulated by adhesion molecules at cell-extracellular matrix (ECM) and cell-cell junctions. Integrin, a transmembrane focal adhesion protein, plays an indispensable role in these immune cell mechanisms.