Read on to learn more about the image featured on the latest issue of the Biophysical Journal! Author Arthur J. Michaelk describes the experiment and findings, as well as the illustrative composition of this issues cover art. The image is passed on the paper, Phosphorylation Modulates Mechanical Stability of the Cardiac Myosin-Binding Protein C Motif, written by Arthur J. Michalek, Jack W. Howarth, James Gulick, Michael J. Previs, Jeffrey Robbins, Paul R. Rosevear, and David M. Warshaw.
Cardiac myosin binding protein-C (cMyBP-C) is a component of the heart’s contractile machinery and is believed to regulate cardiac contractility. While there is a clear link between mutations in cMyBP-C and cardiac pathology, the underlying mechanisms of how this protein modulates cardiac function and how its modulation is affected by post-translational modifications are largely unknown. The N-terminal portion, or business-end, of the protein is made up of a series of stable (immunoglobulin-like, in yellow) and disordered (in blue and red) domains. We hypothesized that free extensibility of these disordered domains is essential to cMyBP-C function. Atomic force spectroscopy, in which a protein is stretched between an AFM probe and a glass slide allowed us to measure extensibility at the single molecule level.
Our central finding was that the un-phosphorylated M-domain (shown in red) was freely extensible and presumably disordered but upon phosphorylation at four sites, the M-domain was no longer freely extensible and thus adopted a stable, globular conformation under tensile load as depicted in the illustration. This transition between free extensibility and a more stable conformation points toward a mechanism through which post-translational modification may have a profound impact on cMyBP-C’s molecular mechanics and therefore its regulatory function in the heart.
The image was composed in Blender v2.6, and is drawn approximately to scale, based on the dimensions of the globular protein domains and manufacturer specifications for the AFM probe. The texture of the slide surface was taken from an AFM height image of one of the glass microscope slides used in the study. One of the biggest challenges of doing research in single molecule biophysics is never being able to actually see any of my specimens. At the same time, this creates a great opportunity to imagine what my assay would look like if I could see it. I have found illustrations to be critical in helping to communicate the link between my raw data and what it represents. I chose to prepare a cover illustration to go along with my manuscript, because it offered the potential to expose my work to a broad audience, and it is a great honor to see both my research and my illustration featured prominently in the Biophysical Journal.
More information about our work can be found on our lab web site: