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Binding of F‐actin to the Cardiac Myosin Binding Protein C (MYBPC3) M Domain
Author(s) -
Patton Connor,
Van Heidi,
Hoffman Matthew,
DhePaga Sirano,
Gilbert Richard
Publication year - 2015
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.29.1_supplement.712.15
Subject(s) - titin , actin , myofilament , sarcomere , myosin , binding domain , actin binding protein , microbiology and biotechnology , biology , heavy meromyosin , chemistry , biochemistry , myosin light chain kinase , actin cytoskeleton , binding site , cytoskeleton , myocyte , cell
A common feature in most forms of heart failure is an abnormality of the intricate machinery of sarcomeric protein interactions. Impaired expression or dysfunction of one such protein (MYBPC3) has been associated with hypertrophic cardiomyopathy and an altered regenerative response to injury. Compelling evidence exists that MYBPC3, acting principally through the phosphorylation of its M domain and associated effects on myofilament binding, plays an important role in the regulation of cardiac mechanics. MYBPC3 interacts with titin and light meromyosin (LMM) via its C‐terminus, whereas interactions of the N‐terminus with actin and myosin S2 sub‐fragments are controversial. Given the proximity of the thin filament to the MYBPC3 N‐terminus, it has been hypothesized that actin binding to the N‐terminus domain has fundamental importance in the regulation of sarcomere mechanics. N‐terminal fragments of MYBPC3, containing the M domain, were cloned with histidine tags and expressed and purified in E. coli. Actin was purified from rabbit skeletal muscle acetone powder to form F‐actin and G‐actin monomers, and cross‐linked G‐actin dimers. Employing a Ni‐NTA pull‐down protocol, we demonstrated that the N‐terminal domain fragment of MYBPC3 lacking the C0 subunit binds F‐actin, but not monomeric G‐actin. We conclude that dynamic and selective binding relationships involving the N‐terminus of MYBPC3 and various conformations of actin are fundamental to the control of sarcomeric interactions and may play a role in the pathogenesis of the failing heart. The work represented was supported by NIH RO1 DC 011528.