1SR6

Structure of nucleotide-free scallop myosin S1

Summary for 1SR6

• Entry DOI: 10.2210/pdb1sr6/pdb
• Related: 1KK8 1QVI 1S5G
• Descriptor: Myosin heavy chain, striated muscle, Myosin regulatory light chain, striated adductor muscle, Myosin essential light chain, striated adductor muscle, ... (7 entities in total)
• Functional Keywords: scallop myosin s1, near rigor, complex salt bridge, novel conformation of nucleotide, contractile protein
• Biological source: Argopecten irradians; More
• Cellular location: Cytoplasm, myofibril: P24733
• Total number of polymer chains: 3
• Total formula weight: 131172.00

Authors

Risal, D.,Gourinath, S.,Himmel, D.M.,Szent-Gyorgyi, A.G.,Cohen, C. (deposition date: 2004-03-22, release date: 2004-06-15, Last modification date: 2023-08-23)

Primary citation

Risal, D.,Gourinath, S.,Himmel, D.M.,Szent-Gyorgyi, A.G.,Cohen, C.
Myosin subfragment 1 structures reveal a partially bound nucleotide and a complex salt bridge that helps couple nucleotide and actin binding.
Proc.Natl.Acad.Sci.Usa, 101:8930-8935, 2004

PubMed Abstract: Structural studies of myosin have indicated some of the conformational changes that occur in this protein during the contractile cycle, and we have now observed a conformational change in a bound nucleotide as well. The 3.1-A x-ray structure of the scallop myosin head domain (subfragment 1) in the ADP-bound near-rigor state (lever arm =45 degrees to the helical actin axis) shows the diphosphate moiety positioned on the surface of the nucleotide-binding pocket, rather than deep within it as had been observed previously. This conformation strongly suggests a specific mode of entry and exit of the nucleotide from the nucleotide-binding pocket through the so-called "front door." In addition, using a variety of scallop structures, including a relatively high-resolution 2.75-A nucleotide-free near-rigor structure, we have identified a conserved complex salt bridge connecting the 50-kDa upper and N-terminal subdomains. This salt bridge is present only in crystal structures of muscle myosin isoforms that exhibit a strong reciprocal relationship (also known as coupling) between actin and nucleotide affinity.

PubMed: 15184651
DOI: 10.1073/pnas.0403002101

Experimental method

X-RAY DIFFRACTION (2.75 Å)