1tmz
From Proteopedia
TMZIP: A CHIMERIC PEPTIDE MODEL OF THE N-TERMINUS OF ALPHA TROPOMYOSIN, NMR, 15 STRUCTURES
Structural highlights
FunctionGCN4_YEAST Is a transcription factor that is responsible for the activation of more than 30 genes required for amino acid or for purine biosynthesis in response to amino acid or purine starvation. Binds and recognize the DNA sequence: 5'-TGA[CG]TCA-3'. Publication Abstract from PubMedTropomyosins (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. 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[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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