High-speed AFM reveals subsecond dynamics of cardiac thin filaments upon Ca²⁺ activation and heavy meromyosin binding.

ABSTRACT: High-speed atomic force microscopy (HS-AFM) can be used to study dynamic processes with real-time imaging of molecules within 1- to 5-nm spatial resolution. In the current study, we evaluated the 3-state model of activation of cardiac thin filaments (cTFs) isolated as a complex and deposited on a mica-supported lipid bilayer. We studied this complex for dynamic conformational changes 1) at low and high [Ca²⁺] (pCa 9.0 and 4.5), and 2) upon myosin binding to the cTF in the nucleotide-free state or in the presence of ATP. HS-AFM was used to directly visualize the tropomyosin-troponin complex and Ca²⁺-induced tropomyosin movements accompanied by structural transitions of actin monomers within cTFs. Our data show that cTFs at relaxing or activating conditions are not ulti

SUBMITTER: Matusovsky OS 

PROVIDER: S-EPMC6697793 | biostudies-literature | 2019 Aug

REPOSITORIES: biostudies-literature