UFD-2 is an adaptor-assisted E3 ligase targeting unfolded proteins.

Doris Hellerschmied, Max Roessler, Anita Lehner, Linn Gazda, Karel Stejskal, Richard Imre, Karl Mechtler, Alexander Dammermann, Tim Clausen

Nature communications 2018 Feb 02

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Muscle development requires the coordinated activities of specific protein folding and degradation factors. UFD-2, a U-box ubiquitin ligase, has been reported to play a central role in this orchestra regulating the myosin chaperone UNC-45. Here, we apply an integrative in vitro and in vivo approach to delineate the substrate-targeting mechanism of UFD-2 and elucidate its distinct mechanistic features as an E3/E4 enzyme. Using Caenorhabditis elegans as model system, we demonstrate that UFD-2 is not regulating the protein levels of UNC-45 in muscle cells, but rather shows the characteristic properties of a bona fide E3 ligase involved in protein quality control. Our data demonstrate that UFD-2 preferentially targets unfolded protein segments. Moreover, the UNC-45 chaperone can serve as an adaptor protein of UFD-2 to poly-ubiquitinate unfolded myosin, pointing to a possible role of the UFD-2/UNC-45 pair in maintaining proteostasis in muscle cells.

Citation

Doris Hellerschmied, Max Roessler, Anita Lehner, Linn Gazda, Karel Stejskal, Richard Imre, Karl Mechtler, Alexander Dammermann, Tim Clausen. UFD-2 is an adaptor-assisted E3 ligase targeting unfolded proteins. Nature communications. 2018 Feb 02;9(1):484