Lecture

Molecular Chaperone Action: Small Heat Shock Proteins

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Description

This lecture explores the molecular chaperone action of small heat shock proteins (sHsps) in proteostasis, focusing on their interaction with misfolded proteins, amyloid fibrils, and clients like CLIC1. The lecture delves into the complex and dynamic Hsp chaperone network, the mechanism of sHsps binding to mature amyloid fibrils, and their role in inhibiting fibril-associated cytotoxicity. Through single-molecule fluorescence techniques, the lecture investigates the stoichiometry and subunit architecture of sHsp-client protein complexes, providing insights into the chaperone activity of sHsps. The findings suggest that sHsps stabilize amyloid fibrils, prevent fragmentation, and mitigate fibril-associated cytotoxicity, shedding light on the potential therapeutic implications of sHsps in protein misfolding diseases.

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Related concepts (32)

Chaperone (protein)

In molecular biology, molecular chaperones are proteins that assist the conformational folding or unfolding of large proteins or macromolecular protein complexes. There are a number of classes of molecular chaperones, all of which function to assist large proteins in proper protein folding during or after synthesis, and after partial denaturation. Chaperones are also involved in the translocation of proteins for proteolysis. The first molecular chaperones discovered were a type of assembly chaperones which assist in the assembly of nucleosomes from folded histones and DNA.

Protein folding

Protein folding is the physical process where a protein chain is translated into its native three-dimensional structure, typically a "folded" conformation, by which the protein becomes biologically functional. Via an expeditious and reproducible process, a polypeptide folds into its characteristic three-dimensional structure from a random coil. Each protein exists first as an unfolded polypeptide or random coil after being translated from a sequence of mRNA into a linear chain of amino acids.

Protein aggregation

In molecular biology, protein aggregation is a phenomenon in which intrinsically-disordered or mis-folded proteins aggregate (i.e., accumulate and clump together) either intra- or extracellularly. Protein aggregates have been implicated in a wide variety of diseases known as amyloidoses, including ALS, Alzheimer's, Parkinson's and prion disease. After synthesis, proteins typically fold into a particular three-dimensional conformation that is the most thermodynamically favorable: their native state.

Heat shock response

The heat shock response (HSR) is a cell stress response that increases the number of molecular chaperones to combat the negative effects on proteins caused by stressors such as increased temperatures, oxidative stress, and heavy metals. In a normal cell, proteostasis (protein homeostasis) must be maintained because proteins are the main functional units of the cell. Many proteins take on a defined configuration in a process known as protein folding in order to perform their biological functions.

Amyloid

Amyloids are aggregates of proteins characterised by a fibrillar morphology of typically 7–13 nm in diameter, a β-sheet secondary structure (known as cross-β) and ability to be stained by particular dyes, such as Congo red. In the human body, amyloids have been linked to the development of various diseases. Pathogenic amyloids form when previously healthy proteins lose their normal structure and physiological functions (misfolding) and form fibrous deposits within and around cells.

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