Crystal structure of a vertebrate smooth muscle myosin motor domain and its complex with the essential light chain: visualization of the pre-power stroke state.
The crystal structures of an expressed vertebrate smooth muscle myosin motor domain (MD) and a motor domain-essential light chain (ELC) complex (MDE), both with a transition state analog (MgADP x AIF4-) in the active site, have been determined to 2.9 A and 3.5 A resolution, respectively. The MDE structure with an ATP analog (MgADP x BeFx) was also determined to 3.6 A resolution. In all three structures, a domain of the C-terminal region, the "converter," is rotated approximately 70 degrees from that in nucleotide-free skeletal subfragment 1 (S1). We have found that the MDE-BeFx and MDE-AIF4- structures are almost identical, consistent with the fact that they both bind weakly to actin. A comparison of the lever arm positions in MDE-AIF4- and in nucleotide-free skeletal S1 shows that a potential displacement of approximately 10 nm can be achieved during the power stroke.
Dominguez
R
R
Rosenstiel Basic Medical Sciences Research Center, Brandeis University, Waltham, Massachusetts 02454-9110, USA.
Freyzon
Y
Y
Trybus
K M
KM
Cohen
C
C
D000199:Actins / Q000378:metabolism; D000244:Adenosine Diphosphate / Q000378:metabolism; D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites; D002645:Chickens; D018360:Crystallography, X-Ray; D004023:Dictyostelium; D046911:Macromolecular Substances; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009130:Muscle, Smooth / Q000737:chemistry* / Q000378:metabolism; D018994:Myosin Light Chains / Q000737:chemistry* / Q000378:metabolism; D015879:Myosin Subfragments / Q000737:chemistry* / Q000378:metabolism; D011487:Protein Conformation; D017434:Protein Structure, Tertiary
D000199:Actins; D046911:Macromolecular Substances; D018994:Myosin Light Chains; D015879:Myosin Subfragments; D000244:Adenosine Diphosphate