Fluorescence lifetime of actin in the familial hypertrophic cardiomyopathy transgenic heart

P. Mettikolla, R. Luchowski, I. Gryczynski, Z. Gryczynski, Danuta Szczesna-Cordary, J. Borejdo

Research output: Contribution to journalArticle

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Abstract

Clinical studies have revealed that the D166V mutation in the ventricular myosin regulatory light chain (RLC) can cause a malignant phenotype of familial hypertrophic cardiomyopathy (FHC). It has been proposed that RLC induced FHC in the heart originates at the level of the myosin cross-bridge due to alterations in the rates of cross-bridge cycling. In this report, we examine whether the environment of an active cross-bridge in cardiac myofibrils from transgenic (Tg) mice is altered by the D166V mutation in RLC. The cross-bridge environment was monitored by tracking the fluorescence lifetime (τ) of Alexa488-phalloidin- labeled actin. The fluorescence lifetime is the average rate of decay of a fluorescent species from the excited state, which strongly depends on various environmental factors. We observed that the lifetime was high when cross-bridges were bound to actin and low when they were dissociated from it. The lifetime was measured every 50 ms from the center half of the I-band during 60 s of rigor, relaxation and contraction of muscle. We found no differences between lifetimes of Tg-WT and Tg-D166V muscle during rigor, relaxation and contraction. The duty ratio expressed as a fraction of time that cross-bridges spend attached to the thin filaments during isometric contraction was similar in Tg-WT and Tg-D166V muscles. Since independent measurements showed a large decrease in the cross-bridge turnover rate in Tg-D166V muscle compared to Tg-WT, the fact that the duty cycle remains constant suggests that the D166V mutation of RLC causes a decrease in the rate of cross-bridge attachment to actin.

Original languageEnglish
Pages (from-to)1264-1271
Number of pages8
JournalBiochemistry
Volume48
Issue number6
DOIs
StatePublished - Feb 17 2009

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Familial Hypertrophic Cardiomyopathy
Actins
Fluorescence
Light
Muscles
Mutation
Ventricular Myosins
Muscle
Phalloidine
Myosin Light Chains
Isometric Contraction
Muscle Relaxation
Myofibrils
Myosins
Muscle Contraction
Transgenic Mice
Phenotype
Excited states

ASJC Scopus subject areas

  • Biochemistry

Cite this

Mettikolla, P., Luchowski, R., Gryczynski, I., Gryczynski, Z., Szczesna-Cordary, D., & Borejdo, J. (2009). Fluorescence lifetime of actin in the familial hypertrophic cardiomyopathy transgenic heart. Biochemistry, 48(6), 1264-1271. https://doi.org/10.1021/bi801629d

Fluorescence lifetime of actin in the familial hypertrophic cardiomyopathy transgenic heart. / Mettikolla, P.; Luchowski, R.; Gryczynski, I.; Gryczynski, Z.; Szczesna-Cordary, Danuta; Borejdo, J.

In: Biochemistry, Vol. 48, No. 6, 17.02.2009, p. 1264-1271.

Research output: Contribution to journalArticle

Mettikolla, P, Luchowski, R, Gryczynski, I, Gryczynski, Z, Szczesna-Cordary, D & Borejdo, J 2009, 'Fluorescence lifetime of actin in the familial hypertrophic cardiomyopathy transgenic heart', Biochemistry, vol. 48, no. 6, pp. 1264-1271. https://doi.org/10.1021/bi801629d
Mettikolla, P. ; Luchowski, R. ; Gryczynski, I. ; Gryczynski, Z. ; Szczesna-Cordary, Danuta ; Borejdo, J. / Fluorescence lifetime of actin in the familial hypertrophic cardiomyopathy transgenic heart. In: Biochemistry. 2009 ; Vol. 48, No. 6. pp. 1264-1271.
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