Lee, C.F., Hauenstein, A.V., Fleming, J.K., Gasper, W.C., Engelke, V., Sankaran, B., Bernstein, S.I., Huxford, T. (2011). X-ray Crystal Structure of the UCS Domain-Containing UNC-45 Myosin Chaperone from Drosophila melanogaster. Structure 19(3): 397--408.
FlyBase ID
FBrf0213235
Publication Type
Research paper
Abstract
UCS proteins, such as UNC-45, influence muscle contraction and other myosin-dependent motile processes. We report the first X-ray crystal structure of a UCS domain-containing protein, the UNC-45 myosin chaperone from Drosophila melanogaster (DmUNC-45). The structure reveals that the central and UCS domains form a contiguous arrangement of 17 consecutive helical layers that arrange themselves into five discrete armadillo repeat subdomains. Small-angle X-ray scattering data suggest that free DmUNC-45 adopts an elongated conformation and exhibits flexibility in solution. Protease sensitivity maps to a conserved loop that contacts the most carboxy-terminal UNC-45 armadillo repeat subdomain. Amino acid conservation across diverse UCS proteins maps to one face of this carboxy-terminal subdomain, and the majority of mutations that affect myosin-dependent cellular activities lie within or around this region. Our crystallographic, biophysical, and biochemical analyses suggest that DmUNC-45 function is afforded by its flexibility and by structural integrity of its UCS domain.
