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Publication Abstract from PubMed

The UCS (UNC-45/CRO1/She4) chaperones play an evolutionarily conserved role in promoting myosin-dependent processes, including cytokinesis, endocytosis, RNA transport, and muscle development. To investigate the protein machinery orchestrating myosin folding and assembly, we performed a comprehensive analysis of Caenorhabditis elegans UNC-45. Our structural and biochemical data demonstrate that UNC-45 forms linear protein chains that offer multiple binding sites for cooperating chaperones and client proteins. Accordingly, Hsp70 and Hsp90, which bind to the TPR domain of UNC-45, could act in concert and with defined periodicity on captured myosin molecules. In vivo analyses reveal the elongated canyon of the UCS domain as a myosin-binding site and show that multimeric UNC-45 chains support organization of sarcomeric repeats. In fact, expression of transgenes blocking UNC-45 chain formation induces dominant-negative defects in the sarcomere structure and function of wild-type worms. Together, these findings uncover a filament assembly factor that directly couples myosin folding with myofilament formation.

The myosin chaperone UNC-45 is organized in tandem modules to support myofilament formation in C. elegans.,Gazda L, Pokrzywa W, Hellerschmied D, Lowe T, Forne I, Mueller-Planitz F, Hoppe T, Clausen T Cell. 2013 Jan 17;152(1-2):183-95. doi: 10.1016/j.cell.2012.12.025. PMID:23332754^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.