In vitro and in vivo single myosin step-sizes in striated muscle

Thomas P Burghardt, Xiaojing Sun, Yihua Wang, Katalin Ajtai

Research output: Contribution to journalArticle

4 Citations (Scopus)

Abstract

Myosin in muscle transduces ATP free energy into the mechanical work of moving actin. It has a motor domain transducer containing ATP and actin binding sites, and, mechanical elements coupling motor impulse to the myosin filament backbone providing transduction/mechanical-coupling. The mechanical coupler is a lever-arm stabilized by bound essential and regulatory light chains. The lever-arm rotates cyclically to impel bound filamentous actin. Linear actin displacement due to lever-arm rotation is the myosin step-size. A high-throughput quantum dot labeled actin in vitro motility assay (Qdot assay) measures motor step-size in the context of an ensemble of actomyosin interactions. The ensemble context imposes a constant velocity constraint for myosins interacting with one actin filament. In a cardiac myosin producing multiple step-sizes, a “second characterization” is step-frequency that adjusts longer step-size to lower frequency maintaining a linear actin velocity identical to that from a shorter step-size and higher frequency actomyosin cycle. The step-frequency characteristic involves and integrates myosin enzyme kinetics, mechanical strain, and other ensemble affected characteristics. The high-throughput Qdot assay suits a new paradigm calling for wide surveillance of the vast number of disease or aging relevant myosin isoforms that contrasts with the alternative model calling for exhaustive research on a tiny subset myosin forms. The zebrafish embryo assay (Z assay) performs single myosin step-size and step-frequency assaying in vivo combining single myosin mechanical and whole muscle physiological characterizations in one model organism. The Qdot and Z assays cover “bottom-up” and “top-down” assaying of myosin characteristics.

Original languageEnglish (US)
Pages (from-to)1-15
Number of pages15
JournalJournal of Muscle Research and Cell Motility
DOIs
StateAccepted/In press - Jan 4 2016

Fingerprint

Striated Muscle
Myosins
Muscle
Actins
Assays
Actomyosin
Throughput
In Vitro Techniques
Cardiac Myosins
Quantum Dots
Muscles
Enzyme kinetics
Stepping motors
Zebrafish
Transducers
Actin Cytoskeleton
Free energy
Semiconductor quantum dots
Protein Isoforms
Embryonic Structures

Keywords

  • Cardiac myosin step-frequency
  • Cardiac myosin step-size
  • High throughput Qdot assay
  • In vivo single myosin imaging
  • Second characterization
  • Skeletal muscle myosin mechanics

ASJC Scopus subject areas

  • Physiology
  • Cell Biology
  • Biochemistry

Cite this

In vitro and in vivo single myosin step-sizes in striated muscle. / Burghardt, Thomas P; Sun, Xiaojing; Wang, Yihua; Ajtai, Katalin.

In: Journal of Muscle Research and Cell Motility, 04.01.2016, p. 1-15.

Research output: Contribution to journalArticle

Burghardt, Thomas P ; Sun, Xiaojing ; Wang, Yihua ; Ajtai, Katalin. / In vitro and in vivo single myosin step-sizes in striated muscle. In: Journal of Muscle Research and Cell Motility. 2016 ; pp. 1-15.
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