What question did this study set out to answer?

To determine how nucleotide binding and actin interactions drive conformational changes in the local environment of Lys553 within the strong actin-binding region of myosin subfragment 1.

July 15, 1999European Journal of BiochemistryOpen Access

Actin and nucleotide induced conformational changes in the vicinity of Lys553 in myosin subfragment 1

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Population

Myosin subfragment 1 (S1)

Design

Preclinical

Authors

YPY. Michael PeyserHebrew University of Jerusalem AMAndrás MühlrádHebrew University of Jerusalem

Discussion

Member takes

Implication

No immediate clinical implications in cardiology; leaves open myosin conformational dynamics for mechanistic research.

Key Points

To determine how nucleotide binding and actin interactions drive conformational changes in the local environment of Lys553 within the strong actin-binding region of myosin subfragment 1.
Monitored modification kinetics of Lys553 in myosin subfragment 1 using the selective fluorophore 6-[fluoresceine-5(and 6)-carboxamido] hexanoic acid succinimidyl ester (FHS).
Evaluated labeling rates under varied pH, ionic strength (0.4 M KCl), limited trypsin digestion, and in the presence of actin or nucleotide analogs (ATP, ADP, ADP·BeFx, ADP·AlF4-, ADP·Vi, and pyrophosphate).
Measured nitromethane quenching of Lys553-bound fluorophores to distinguish steric hindrance from allosteric conformational changes.
Nucleotides and actin significantly reduced the rate of Lys553 modification without altering nitromethane fluorescence quenching, showing that altered reactivity arises from conformational shifts rather than steric occlusion.
ATP decreased the labeling rate more substantially than transition-state analogs ADP·AlF4(-) and ADP·Vi, revealing that analog complexes do not fully duplicate the Lys553 local conformation of the authentic M**·ADP·Pi state.
High ionic strength (0.4 M KCl) and limited trypsinolysis significantly decreased labeling rates, whereas elevated pH increased reactivity by promoting the unprotonated epsilon-amino form of Lys553.

Structured PICO

Population

Myosin subfragment 1 (S1)

Intervention

Actin and various nucleotides (ATP, ADP, ADP.BeF(x), ADP.AlF(4), ADP.V(i), pyrophosphate)

Outcome

Rate of Lys553 labelling by 6-[fluoresceine-5(and 6)-carboxamido] hexanoic acid succinimidyl ester (FHS)surrogate

Actin and nucleotides induce conformational changes in the vicinity of Lys553 in myosin subfragment 1, affecting its chemical reactivity but not accessibility.

Cite This Study

Peyser et al. (1999) studied this question.

synapsesocial.com/papers/6a800ffb826e8e37b93d406f https://doi.org/10.1046/j.1432-1327.1999.00530.x

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Actin and nucleotide induced conformational changes in the vicinity of Lys553 in myosin subfragment 1

Discussion

Member takes

Implication

Key Points

Structured PICO

Cite This Study

Actin and nucleotide induced conformational changes in the vicinity of Lys553 in myosin subfragment 1

Discussion

Member takes

Implication

Key Points

Structured PICO

Cite This Study

Also Consider

Also Consider