Issue 42, 2019

Conformation switching of single native proteins revealed by nanomechanical probing without a pulling force

Abstract

Protein conformational changes are essential to biological function, and the heterogeneous nature of the corresponding protein states provokes an interest to measure conformational changes at the single molecule level. Here we demonstrate that conformational changes in single native proteins can be revealed by non-covalent antibody-targeting of specific domains within the protein, using nanomechanical probing without an applied pulling force. The protein of interest was captured between a particle and a substrate and three properties were quantified: the twist amplitude related to an applied torque, torsional compliance related to rotational Brownian motion, and translational Brownian displacement. Calcium-dependent conformation switching was studied in native human cardiac troponin, a heterotrimer protein complex that regulates the contraction and relaxation of heart muscle cells and is also a key biomarker for diagnosing myocardial infarction. The data reveal a change in mechanical properties upon conformation switching from the non-saturated to the calcium-saturated state, which in cardiomyocytes gives myosin motor proteins access to actin filaments. A clear increase was observed in the molecular stiffness for the calcium-saturated protein conformation. Using libraries of monoclonal antibodies, the nanomechanical probing of conformation by antibody targeting opens avenues for characterizing single native protein complexes for research as well as for diagnostic applications.

Graphical abstract: Conformation switching of single native proteins revealed by nanomechanical probing without a pulling force

Supplementary files

Article information

Article type
Paper
Submitted
16 Feb 2019
Accepted
23 Sep 2019
First published
24 Sep 2019
This article is Open Access
Creative Commons BY-NC license

Nanoscale, 2019,11, 19933-19942

Conformation switching of single native proteins revealed by nanomechanical probing without a pulling force

F. A. Gutiérrez-Mejía, C. P. Moerland, L. J. van IJzendoorn and M. W. J. Prins, Nanoscale, 2019, 11, 19933 DOI: 10.1039/C9NR01448A

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