1tmz

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TMZIP: A CHIMERIC PEPTIDE MODEL OF THE N-TERMINUS OF ALPHA TROPOMYOSIN, NMR, 15 STRUCTURES

Overview

Tropomyosins (TMs) are highly conserved, coiled-coil, actin binding, regulatory proteins found in most eukaryotic cells. The amino-terminal, domain of 284-residue TMs is among the most conserved and functionally, important regions. The first nine residues are proposed to bind to the, carboxyl-terminal nine residues to form the "overlap" region between, successive TMs, which bind along the actin filament. Here, the structure, of the N-terminus of muscle alpha-TM, in a chimeric peptide, TMZip, has, been solved using circular dichroism (CD) and two-dimensional proton, nuclear magnetic resonance (2D 1H NMR) spectroscopy. Residues 1-14 of, TMZip are the first 14 N-terminal residues of rabbit striated alpha-TM, and residues 15-32 of TMZip are the last 18 C-terminal residues of the, yeast GCN4 transcription factor. CD measurements show that TMZip forms a, two-stranded coiled-coil alpha-helix with an enthalpy of folding of -34, +/- 2 kcal/mol. In 2D1H NMR studies at 15 degrees C, pH 6.4, the peptide, exhibits 123 sequential and medium range intrachain NOE cross peaks per, chain, characteristic of alpha-helices extending from residue 1 to residue, 29, together with 85 long-range NOE cross peaks arising from interchain, interactions. The three-dimensional structure of TMZip has been determined, using these data plus an additional 509 intrachain constraints per chain., The coiled-coil domain extends to the N-terminus. Amide hydrogen exchange, studies, however, suggest that the TM region is less stable than the GCN4, region. The work reported here is the first atomic-resolution structure of, any region of TM and it allows insight into the mechanism of the function, of the highly conserved N-terminal domain.

About this Structure

1TMZ is a Single protein structure of sequence from Rattus norvegicus. Full crystallographic information is available from OCA.

Reference

The structure of the N-terminus of striated muscle alpha-tropomyosin in a chimeric peptide: nuclear magnetic resonance structure and circular dichroism studies., Greenfield NJ, Montelione GT, Farid RS, Hitchcock-DeGregori SE, Biochemistry. 1998 May 26;37(21):7834-43. PMID:9601044

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