N-Terminus of Cardiac Myosin Essential Light Chain Modulates Myosin Step-Size

Yihua Wang, Katalin Ajtai, Katarzyna Kazmierczak, Danuta Szczesna-Cordary, Thomas P. Burghardt

Research output: Contribution to journalArticle

12 Citations (Scopus)

Abstract

Muscle myosin cyclically hydrolyzes ATP to translate actin. Ventricular cardiac myosin (βmys) moves actin with three distinct unitary step-sizes resulting from its lever-arm rotation and with step-frequencies that are modulated in a myosin regulation mechanism. The lever-arm associated essential light chain (vELC) binds actin by its 43 residue N-terminal extension. Unitary steps were proposed to involve the vELC N-terminal extension with the 8 nm step engaging the vELC/actin bond facilitating an extra ∼19 degrees of lever-arm rotation while the predominant 5 nm step forgoes vELC/actin binding. A minor 3 nm step is the unlikely conversion of the completed 5 to the 8 nm step. This hypothesis was tested using a 17 residue N-terminal truncated vELC in porcine βmys (Δ17βmys) and a 43 residue N-terminal truncated human vELC expressed in transgenic mouse heart (Δ43αmys). Step-size and step-frequency were measured using the Qdot motility assay. Both Δ17βmys and Δ43αmys had significantly increased 5 nm step-frequency and coincident loss in the 8 nm step-frequency compared to native proteins suggesting the vELC/actin interaction drives step-size preference. Step-size and step-frequency probability densities depend on the relative fraction of truncated vELC and relate linearly to pure myosin species concentrations in a mixture containing native vELC homodimer, two truncated vELCs in the modified homodimer, and one native and one truncated vELC in the heterodimer. Step-size and step-frequency, measured for native homodimer and at two or more known relative fractions of truncated vELC, are surmised for each pure species by using a new analytical method.

Original languageEnglish (US)
Pages (from-to)186-198
Number of pages13
JournalBiochemistry
Volume55
Issue number1
DOIs
StatePublished - Jan 19 2016

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Cardiac Myosins
Myosin Light Chains
Myosins
Actins
Ventricular Myosins
Transgenic Mice
Muscle
Assays
Swine
Adenosine Triphosphate
Light
Muscles

ASJC Scopus subject areas

  • Biochemistry

Cite this

N-Terminus of Cardiac Myosin Essential Light Chain Modulates Myosin Step-Size. / Wang, Yihua; Ajtai, Katalin; Kazmierczak, Katarzyna; Szczesna-Cordary, Danuta; Burghardt, Thomas P.

In: Biochemistry, Vol. 55, No. 1, 19.01.2016, p. 186-198.

Research output: Contribution to journalArticle

Wang, Yihua ; Ajtai, Katalin ; Kazmierczak, Katarzyna ; Szczesna-Cordary, Danuta ; Burghardt, Thomas P. / N-Terminus of Cardiac Myosin Essential Light Chain Modulates Myosin Step-Size. In: Biochemistry. 2016 ; Vol. 55, No. 1. pp. 186-198.
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