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Elsevier, Biophysical Journal, 11(103), p. 2361-2368, 2012

DOI: 10.1016/j.bpj.2012.10.035

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The Molecular Mechanism Underlying Mechanical Anisotropy of the Protein GB1

Journal article published in 2012 by Yongnan Devin Li, Guillaume Lamour, Jörg Gsponer, Peng Zheng ORCID, Hongbin Li
This paper is made freely available by the publisher.
This paper is made freely available by the publisher.

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Abstract

Mechanical responses of elastic proteins are crucial for their biological function and nanotechnological use. Loading direction has been identified as one key determinant for the mechanical responses of proteins. However, it is not clear how a change in pulling direction changes the mechanical unfolding mechanism of the protein. Here, we combine protein engineering, single-molecule force spectroscopy, and steered molecular dynamics simulations to systematically investigate the mechanical response of a small globular protein GB1. Force versus extension profiles from both experiments and simulations reveal marked mechanical anisotropy of GB1. Using native contact analysis, we relate the mechanically robust shearing geometry with concurrent rupture of native contacts. This clearly contrasts the sequential rupture observed in simulations for the mechanically labile peeling geometry. Moreover, we identify multiple distinct mechanical unfolding pathways in two loading directions. Implications of such diverse unfolding mechanisms are discussed. Our results may also provide some insights for designing elastomeric proteins with tailored mechanical properties.