Protein aggregation and misfolding underpin several neurodegenerative diseases such as Huntington’s and Alzheimer’s. Proteins can also become aggregated or denatured under conditions of stress, such as extreme heat. A new study, published online on March 12, 2020 in the open-access journal PLOS Biology by Dr. Kotaro Tsuboyama and Dr. Yukihide Tomari (photo) of The University of Tokyo, Japan, and colleagues, reveals a newly discovered family of proteins in both humans and flies which protect vulnerable proteins from becoming aggregated or denatured in extreme heat and other stresses – a function previously only known in “extremophile” organisms such as heat-loving bacteria. The PLOS Biology article is titled “A Widespread Family of Heat-Resistant Obscure (Hero) Proteins Protect Against Protein Instability and Aggregation.” The proteins, discovered through a serendipitous observation, may find applications in biotechnology and protection from neurodegenerative disease. Proteins are molecules held in their active folded shape by weak attractions between and among amino acids. Heat can disrupt these attractions, changing protein shape and causing them to clump together. This also stops the proteins from functioning. An entire class of already known proteins—the “molecular chaperones”—use cellular energy in the form of ATP to either refold or dispose of misfolded proteins. But for proteins in most organisms, temperatures close to the boiling point of water irreversibly destroy their structure. In the course of their research on an entirely different question, while trying to purify a structurally unstable fly protein called Ago2, the authors of the PLOS Biology article found that liquid extracted by breaking open fly cells contained some factor that stabilized this Ago2 protein.
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