DOI: 10.1101/492876Dec 10, 2018Paper

Unique unfoldase/aggregase activity of a molecular chaperone that dysregulates a translational elongation factor

BioRxiv : the Preprint Server for Biology
Ku-Sung JoHyung-Sik Won


The various chaperone activities of heat shock proteins contribute to ensuring cellular proteostasis. Here, we demonstrate the non-canonical unfoldase activity as an inherent functionality of the prokaryotic molecular chaperone Hsp33. The holding-inactive, reduced form of Hsp33 (RHsp33) strongly bound to the translational elongation factor, EF-Tu, and catalyzed the EF-Tu aggregation via evoking its aberrant folding, resulting in its susceptibility to proteolytic degradation by Lon. This interaction was critically mediated by the redox-switch domain of RHsp33 and the guanine nucleotide-binding domain of EF-Tu. The RHsp33-induced in vivo aggregation of EF-Tu upon heat shock was evident in a Lon-deficient strain and inhibited cell growth. Unlike wild-type Escherichia coli, the strain lacking both Hsp33 and Lon showed a non-reduced level of EF-Tu and diminished capability of counteracting heat shock. These findings suggest that the unique unfoldase/aggregase activity of Hsp33 potentially involved in protein turnover confers a cellular survival advantage under heat-stressed conditions.

Related Concepts

Cell Growth
Escherichia coli
Heat shock proteins
Protein Folding
Molecular Chaperones
Heat-Shock Response
EEF1A1 protein, human
Guanine nucleotide binding protein
Protein Biosynthesis

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