Mechanical unfolding intermediates in titin modules

Plotr E. Marszalek, Hui Lu, Hongbin Li, Mariano Carrion-Vazquez, Andres Oberhauser, Klaus Schulten, Julio M. Fernandez

Research output: Contribution to journalArticle

639 Citations (Scopus)

Abstract

The modular protein titin, which is responsible for the passive elasticity of muscle, is subjected to stretching forces. Previous work on the experimental elongation of single titin molecules has suggested that force causes consecutive unfolding of each domain in an all-or-none fashion. To avoid problems associated with the heterogeneity of the modular, naturally occurring titin, we engineered single proteins to have multiple copies of single immunoglobulin domains of human cardiac titin. Here we report the elongation of these molecules using the atomic force microscope. We find an abrupt extension of each domain by ~7 Å before the first unfolding event. This fast initial extension before a full unfolding event produces a reversible 'unfolding intermediate'. Steered molecular dynamics simulations show that the rupture of a pair of hydrogen bonds near the amino terminus of the protein domain causes an extension of about 6 Å, which is in good agreement with our observations. Disruption of these hydrogen bonds by site- directed mutagenesis eliminates the unfolding intermediate. The unfolding intermediate extends titin domains by ~15% of their slack length, and is therefore likely to be an important previously unrecognized component of titin elasticity.

Original languageEnglish (US)
Pages (from-to)100-103
Number of pages4
JournalNature
Volume402
Issue number6757
DOIs
StatePublished - Nov 4 1999
Externally publishedYes

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Connectin
Elasticity
Hydrogen
Pair Bond
Molecular Dynamics Simulation
Site-Directed Mutagenesis
Rupture
Proteins
Muscles

ASJC Scopus subject areas

  • General

Cite this

Marszalek, P. E., Lu, H., Li, H., Carrion-Vazquez, M., Oberhauser, A., Schulten, K., & Fernandez, J. M. (1999). Mechanical unfolding intermediates in titin modules. Nature, 402(6757), 100-103. https://doi.org/10.1038/47083

Mechanical unfolding intermediates in titin modules. / Marszalek, Plotr E.; Lu, Hui; Li, Hongbin; Carrion-Vazquez, Mariano; Oberhauser, Andres; Schulten, Klaus; Fernandez, Julio M.

In: Nature, Vol. 402, No. 6757, 04.11.1999, p. 100-103.

Research output: Contribution to journalArticle

Marszalek, PE, Lu, H, Li, H, Carrion-Vazquez, M, Oberhauser, A, Schulten, K & Fernandez, JM 1999, 'Mechanical unfolding intermediates in titin modules', Nature, vol. 402, no. 6757, pp. 100-103. https://doi.org/10.1038/47083
Marszalek PE, Lu H, Li H, Carrion-Vazquez M, Oberhauser A, Schulten K et al. Mechanical unfolding intermediates in titin modules. Nature. 1999 Nov 4;402(6757):100-103. https://doi.org/10.1038/47083
Marszalek, Plotr E. ; Lu, Hui ; Li, Hongbin ; Carrion-Vazquez, Mariano ; Oberhauser, Andres ; Schulten, Klaus ; Fernandez, Julio M. / Mechanical unfolding intermediates in titin modules. In: Nature. 1999 ; Vol. 402, No. 6757. pp. 100-103.
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