1MV4

TM9A251-284: A Peptide Model of the C-Terminus of a Rat Striated Alpha Tropomyosin

Summary for 1MV4

• Entry DOI: 10.2210/pdb1mv4/pdb
• Related: 1IC2 1IHQ 1TMZ
• NMR Information: BMRB: 5610
• Descriptor: Tropomyosin 1 alpha chain (1 entity in total)
• Functional Keywords: tropomyosin, exon 9a, actin-binding, troponin binding, muscle, alpha-helix, coiled-coil, dimer, peptide-model, two-chained, disulfide cross-linked, de novo protein
• Biological source: Rattus norvegicus (Norway rat)
• Cellular location: Cytoplasm, cytoskeleton: P04692
• Total number of polymer chains: 2
• Total formula weight: 8355.41

Authors

Greenfield, N.J.,Swapna, G.V.T.,Huang, Y.,Palm, T.,Graboski, S.,Montelione, G.T.,Hitchcock-Degregori, S.E. (deposition date: 2002-09-24, release date: 2003-02-18, Last modification date: 2024-11-20)

Primary citation

Greenfield, N.J.,Swapna, G.V.T.,Huang, Y.,Palm, T.,Graboski, S.,Montelione, G.T.,Hitchcock-DeGregori, S.E.
The Structure of the Carboxyl Terminus of Striated alpha-Tropomyosin in Solution Reveals an Unusual Parallel Arrangement of Interacting alpha-Helices
Biochemistry, 42:614-619, 2003

PubMed Abstract: Coiled coils are well-known as oligomerization domains, but they are also important sites of protein-protein interactions. We determined the NMR solution structure and backbone (15)N relaxation rates of a disulfide cross-linked, two-chain, 37-residue polypeptide containing the 34 C-terminal residues of striated muscle alpha-tropomyosin, TM9a(251-284). The peptide binds to the N-terminal region of TM and to the tropomyosin-binding domain of the regulatory protein, troponin T. Comparison of the NMR solution structure of TM9a(251-284) with the X-ray structure of a related peptide [Li, Y., Mui, S., Brown, J. H., Strand, J., Reshetnikova, L., Tobacman, L. S., and Cohen, C. (2002) Proc. Natl. Acad. Sci. U.S.A. 99, 7378-7383] reveals significant differences. In solution, residues 253-269 (like most of the tropomyosin molecule) form a canonical coiled coil. Residues 270-279, however, are parallel, linear helices, novel for tropomyosin. The packing between the parallel helices results from unusual interface residues that are atypical for coiled coils. Y267 has poor packing at the coiled-coil interface and a lower R(2) relaxation rate than neighboring residues, suggesting there is conformational flexibility around this residue. The last five residues are nonhelical and flexible. The exposed surface presented by the parallel helices, and the flexibility around Y267 and the ends, may facilitate binding to troponin T and formation of complexes with the N-terminus of tropomyosin and actin. We propose that unusual packing and flexibility are general features of coiled-coil domains in proteins that are involved in intermolecular interactions.

PubMed: 12534273
DOI: 10.1021/bi026989e

Experimental method

SOLUTION NMR