2B9C

Structure of tropomyosin's mid-region: bending and binding sites for actin

Summary for 2B9C

• Entry DOI: 10.2210/pdb2b9c/pdb
• Descriptor: striated-muscle alpha tropomyosin (2 entities in total)
• Functional Keywords: alpha-helix, coiled coil, alanine, axial stagger, radius, side-chain packing, crystal packing, temperature factor, cardiomyopathy, elongated protein, contractile protein
• Biological source: Rattus norvegicus (Norway rat)
• Cellular location: Cytoplasm, cytoskeleton : P04692
• Total number of polymer chains: 2
• Total formula weight: 34266.52

Authors

Brown, J.H.,Zhou, Z.,Reshetnikova, L.,Robinson, H.,Yammani, R.D.,Tobacman, L.S.,Cohen, C. (deposition date: 2005-10-11, release date: 2006-01-03, Last modification date: 2024-10-30)

Primary citation

Brown, J.H.,Zhou, Z.,Reshetnikova, L.,Robinson, H.,Yammani, R.D.,Tobacman, L.S.,Cohen, C.
Structure of the mid-region of tropomyosin: Bending and binding sites for actin.
Proc.Natl.Acad.Sci.Usa, 102:18878-18883, 2005

PubMed Abstract: Tropomyosin is a two-chain alpha-helical coiled coil whose periodic interactions with the F-actin helix are critical for thin filament stabilization and the regulation of muscle contraction. Here we deduce the mechanical and chemical basis of these interactions from the 2.3-A-resolution crystal structure of the middle three of tropomyosin's seven periods. Geometrically specific bends of the coiled coil, produced by clusters of core alanines, and variable bends about gaps in the core, produced by isolated alanines, occur along the molecule. The crystal packing is notable in signifying that the functionally important fifth period includes an especially favorable protein-binding site, comprising an unusual apolar patch on the surface together with surrounding charged residues. Based on these and other results, we have constructed a specific model of the thin filament, with the N-terminal halves of each period (i.e., the so-called "alpha zones") of tropomyosin axially aligned with subdomain 3 of each monomer in F-actin.

PubMed: 16365313
DOI: 10.1073/pnas.0509269102

Experimental method

X-RAY DIFFRACTION (2.3 Å)