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Titolo:
IMMUNOGLOBULIN-TYPE DOMAINS OF TITIN - SAME FOLD, DIFFERENT STABILITY
Autore:
POLITOU AS; GAUTEL M; PFUHL M; LABEIT S; PASTORE A;
Indirizzi:
EUROPEAN MOLEC BIOL LAB,MEYERHOFSTR 1 D-69117 HEIDELBERG GERMANY
Titolo Testata:
Biochemistry
fascicolo: 15, volume: 33, anno: 1994,
pagine: 4730 - 4737
SICI:
0006-2960(1994)33:15<4730:IDOT-S>2.0.ZU;2-Q
Fonte:
ISI
Lingua:
ENG
Soggetto:
PROTEIN SECONDARY STRUCTURE; CIRCULAR-DICHROISM SPECTRA; SKELETAL-MUSCLE; NMR-SPECTROSCOPY; CHEMICAL-SHIFT; PH-DEPENDENCE; BETA-SHEET; FILAMENTS; PURIFICATION; SUPERFAMILY;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Science Citation Index Expanded
Citazioni:
62
Recensione:
Indirizzi per estratti:
Citazione:
A.S. Politou et al., "IMMUNOGLOBULIN-TYPE DOMAINS OF TITIN - SAME FOLD, DIFFERENT STABILITY", Biochemistry, 33(15), 1994, pp. 4730-4737

Abstract

Titin is a 3-MDa protein thought to form a fibrous intracellular system in vertebrate striated muscle and to play an important role in sarcomere alignment during muscle contraction. It has also been implicatedas a ''molecular ruler'', regulating the assembly and the precise length of the thick filaments Whiting, A. J., Wardale, J., & Trinick, J. (1989) J. Mol. Biol. 205, 163-169. Partial sequencing of titin-encoding cDNAs suggests that the protein is organized in a modular fashion,containing two classes of similar to 100-residue repeats Labeit, S.,Barlow, D. P., Gautel, M., Gibson, T., Holt, J., Hsieh, C. L., Francke, U., Leonard, K., Wardale, J., Whiting, A., & Trinick, J. (1990) Nature 345, 273-276. These motifs, referred to as type I and type II modules, show sequence homology to the fibronectin III and immunoglobulinC2 superfamilies, respectively. Since the type II modules represent the most widely occurring motifs along the titin molecule, we expressedin Escherichia coli three domains of this type spanning different regions of the sarcomere (A-band and M-line) and studied their structure and stability. Using circular dichroism, nuclear magnetic resonance, and fluorescence spectroscopy, we showed that all the fragments examined are independently folded in solution and possess a beta-sheet conformation. Furthermore, employing NMR analysis, we identified an overall folding pattern present in all modules and related to the Ig fold, as previously suggested by theoretical predictions. The stability of the modules over a range of conditions was investigated by measuring key thermodynamic parameters for both thermal and chemical denaturation andby monitoring amide proton exchange as a function of time. Despite the overall structural similarity, the stability of the modules seemed to differ; the motif corresponding to the M-line band was significantlymore stable than the motifs corresponding to the A-band. Our data provide direct experimental evidence that the titin type II modules possess a beta-sheet conformation and further suggest that similarly foldedmotifs located at different regions of the titin molecule may have distinct molecular properties and stability. As structural analysis of more titin domains is proceeding, these and related observations are expected to establish clear cut structure-function relationships and to unveil the exact cellular role of this protein.

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Documento generato il 26/11/20 alle ore 20:17:39