title: Cross-species mechanical fingerprinting of cardiac myosin binding protein-C.
abstract: Cardiac myosin binding protein-C (cMyBP-C) is a member of the immunoglobulin (Ig) superfamily of proteins and consists of 8 Ig- and 3 fibronectin III (FNIII)-like domains along with a unique regulatory sequence referred to as the MyBP-C motif or M-domain. We previously used atomic force microscopy to investigate the mechanical properties of murine cMyBP-C expressed using a baculovirus/insect cell expression system. Here, we investigate whether the mechanical properties of cMyBP-C are conserved across species by using atomic force microscopy to manipulate recombinant human cMyBP-C and native cMyBP-C purified from bovine heart. Force versus extension data obtained in velocity-clamp experiments showed that the mechanical response of the human recombinant protein was remarkably similar to that of the bovine native cMyBP-C. Ig/Fn-like domain unfolding events occurred in a hierarchical fashion across a threefold range of forces starting at relatively low forces of ~50 pN and ending with the unfolding of the highest stability domains at ~180 pN. Force-extension traces were also frequently marked by the appearance of anomalous force drops suggestive of additional mechanical complexity such as structural coupling among domains. Both recombinant and native cMyBP-C exhibited a prominent segment ~100 nm-long that could be stretched by forces <50 pN before the unfolding of Ig- and FN-like domains. Combined with our previous observations of mouse cMyBP-C, these results establish that although the response of cMyBP-C to mechanical load displays a complex pattern, it is highly conserved across species.
authors.affiliation: University of California - Davis, Davis, CA, USA.
authors.forename: Árpád
authors.initials: Á
authors.lastname: Karsai
authors.forename: Miklós S Z
authors.initials: MS
authors.lastname: Kellermayer
authors.forename: Samantha P
authors.initials: SP
authors.lastname: Harris
mesh_terms: D000818:Animals; D002352:Carrier Proteins / Q000737:chemistry / Q000378:metabolism*; D002417:Cattle; D006801:Humans; D055595:Mechanical Phenomena; D051379:Mice; D008958:Models, Molecular; D009010:Monte Carlo Method; D017434:Protein Structure, Tertiary; D058767:Protein Unfolding; D011994:Recombinant Proteins / Q000737:chemistry / Q000378:metabolism; D013045:Species Specificity; D000099163:Myosin Binding Protein C
chemical_list: D002352:Carrier Proteins; D011994:Recombinant Proteins; D000099163:Myosin Binding Protein C