3OPB

Crystal structure of She4p

Summary for 3OPB

• Entry DOI: 10.2210/pdb3opb/pdb
• Descriptor: SWI5-dependent HO expression protein 4 (2 entities in total)
• Functional Keywords: heat and arm fold, myosin folding and function, myosin binding protein, protein binding
• Biological source: Saccharomyces cerevisiae (brewer's yeast,lager beer yeast,yeast)
• Cellular location: Cytoplasm (Potential): P51534
• Total number of polymer chains: 2
• Total formula weight: 175761.97

Authors

Shi, H.,Blobel, G. (deposition date: 2010-08-31, release date: 2010-12-01, Last modification date: 2024-02-21)

Primary citation

Shi, H.,Blobel, G.
UNC-45/CRO1/She4p (UCS) protein forms elongated dimer and joins two myosin heads near their actin binding region.
Proc.Natl.Acad.Sci.USA, 107:21382-21387, 2010

PubMed Abstract: UNC-45/CRO1/She4p (UCS) proteins have variously been proposed to affect the folding, stability, and ATPase activity of myosins. They are the only proteins known to interact directly with the motor domain. To gain more insight into UCS function, we determined the atomic structure of the yeast UCS protein, She4p, at 2.9 Å resolution. We found that 16 helical repeats are organized into an L-shaped superhelix with an amphipathic N-terminal helix dangling off the short arm of the L-shaped molecule. In the crystal, She4p forms a 193-Å-long, zigzag-shaped dimer through three distinct and evolutionary conserved interfaces. We have identified She4p's C-terminal region as a ligand for a 27-residue-long epitope on the myosin motor domain. Remarkably, this region consists of two adjacent, but distinct, binding epitopes localized at the nucleotide-responsive cleft between the nucleotide- and actin-filament-binding sites. One epitope is situated inside the cleft, the other outside the cleft. After ATP hydrolysis and Pi ejection, the cleft narrows at its base from 20 to 12 Å thereby occluding the inside the cleft epitope, while leaving the adjacent, outside the cleft binding epitope accessible to UCS binding. Hence, one cycle of higher and lower binding affinity would accompany one ATP hydrolysis cycle and a single step in the walk on an actin filament rope. We propose that a UCS dimer links two myosins at their motor domains and thereby functions as one of the determinants for step size of myosin on actin filaments.

PubMed: 21115842
DOI: 10.1073/pnas.1013038107

Experimental method

X-RAY DIFFRACTION (2.9 Å)