Cardiomyopathy-linked myosin regulatory light chain mutations disrupt myosin strain-dependent biochemistry

Greenberg, Michael J.; Kazmierczak, Katarzyna; Szczesna‐Cordary, Danuta; Moore, Jeffrey R.

doi:10.1073/pnas.1009619107

Cited by 79 publications

(91 citation statements)

References 35 publications

(66 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…This phenomenon has recently been suggested to be true for cardiac myosin (60). It may be that the cross-bridges in the myofibrils are under some sort of load that would affect the rate of ADP dissociation.…”

Section: Discussionmentioning

confidence: 95%

The Rates of Ca2+ Dissociation and Cross-bridge Detachment from Ventricular Myofibrils as Reported by a Fluorescent Cardiac Troponin C

Little

Biesiadecki

Kilic

et al. 2012

Journal of Biological Chemistry

View full text Add to dashboard Cite

Background:The rate-limiting step of cardiac muscle relaxation is not completely understood. Results: We were able to measure two proposed rate-limiting steps of relaxation in ventricular myofibrils. Conclusion:The rate of Ca 2ϩ dissociation from troponin C may be rate-limiting during myofilament inactivation under physiological conditions. Significance: Strategies that target both troponin C and myosin will be needed to treat diastolic dysfunction.

show abstract

Section: Discussionmentioning

confidence: 95%

The Rates of Ca2+ Dissociation and Cross-bridge Detachment from Ventricular Myofibrils as Reported by a Fluorescent Cardiac Troponin C

Little

Biesiadecki

Kilic

et al. 2012

Journal of Biological Chemistry

View full text Add to dashboard Cite

show abstract

“…The force-dependent behavior of some myosins has been shown to be highly sensitive to the presence of ADP (39,40). Therefore, we performed experiments with the isometric optical clamp engaged in the presence of 50 μM ADP and 1 mM ATP (Fig.…”

Section: Resultsmentioning

confidence: 99%

Myosin IC generates power over a range of loads via a new tension-sensing mechanism

Greenberg

Lin

Goldman

et al. 2012

Proc. Natl. Acad. Sci. U.S.A.

Self Cite

133

View full text Add to dashboard Cite

Myosin IC (myo1c), a widely expressed motor protein that links the actin cytoskeleton to cell membranes, has been associated with numerous cellular processes, including insulin-stimulated transport of GLUT4, mechanosensation in sensory hair cells, endocytosis, transcription of DNA in the nucleus, exocytosis, and membrane trafficking. The molecular role of myo1c in these processes has not been defined, so to better understand myo1c function, we utilized ensemble kinetic and single-molecule techniques to probe myo1c's biochemical and mechanical properties. Utilizing a myo1c construct containing the motor and regulatory domains, we found the force dependence of the actin-attachment lifetime to have two distinct regimes: a force-independent regime at forces <1 pN, and a highly force-dependent regime at higher loads. In this force-dependent regime, forces that resist the working stroke increase the actinattachment lifetime. Unexpectedly, the primary force-sensitive transition is the isomerization that follows ATP binding, not ADP release as in other slow myosins. This force-sensing behavior is unique amongst characterized myosins and clearly demonstrates mechanochemical diversity within the myosin family. Based on these results, we propose that myo1c functions as a slow transporter rather than a tension-sensitive anchor.is a widely expressed myosin-I isoform that has been associated with several important cellular processes, including endocytosis (1), exocytosis (2) (including insulin-stimulated GLUT4 translocation to the cell membrane; refs. 3-5), membrane ruffling (6), transcription of DNA in the nucleus (7,8), and mechanosensing in sensory hair cells (9-13). Although it is known that myo1c links cell membranes to the actin cytoskeleton (14, 15), its molecular role in these cellular processes has not been determined. For example, in its proposed role in exocytosis, it is not known if myo1c acts as a motor for transport, moving vesicles into position for plasma membrane fusion and/or as a tension-sensitive anchor that docks exocytic vesicles to the actin cytoskeleton and plasma membrane.Most members of the myosin family share the same kinetic pathway for ATP hydrolysis, in which force-generating structural changes are linked to release of inorganic phosphate and ADP, but different myosin isoforms have evolved different biochemical reaction rates and force-dependent kinetics to suit their cellular functions. For example, in myosins that are thought to act as tension-sensitive anchors, the kinetic steps that limit actomyosin detachment are highly sensitive to load. In contrast, myosins that are thought to act as transporters have actin-detachment kinetics that are less sensitive to load, allowing work to be performed over a range of forces. Thus, insight into the molecular role of myosin in the cell can be gained from evaluating the kinetic and mechanical properties of the motor.Previous biochemical analyses have shown that myo1c is a lowduty ratio motor (i.e., it spends most of its biochemical cycle detached from act...

show abstract

“…All solutions used for in vitro motility assays were prepared as described previously [30,31] with some modifications (see Table S1 in the Supplementary Information). Imidazole was replaced by BES buffer, and the actin solution contained HDTA.…”

Section: Methodsmentioning

confidence: 99%

Energy landscapes reveal the myopathic effects of tropomyosin mutations

Orzechowski

Fischer

Moore

et al. 2014

Archives of Biochemistry and Biophysics

Self Cite

View full text Add to dashboard Cite

Striated muscle contraction is regulated by an interaction network connecting the effects of troponin, Ca2+, and myosin-heads to the azimuthal positioning of tropomyosin along thin filaments. Many missense mutations, located at the actin-tropomyosin interface, however, reset the regulatory switching mechanism either by weakening or strengthening residue-specific interactions, leading to hyper- or hypo-contractile pathologies. Here, we compute energy landscapes for the actin-tropomyosin interface and quantify contributions of single amino acid residues to actin-tropomyosin binding. The method is a useful tool to assess effects of actin and tropomyosin mutations, potentially relating initial stages of myopathy to alterations in thin filament stability and regulation. Landscapes for mutant filaments linked to hyper-contractility provide a simple picture that describes a decrease in actin-tropomyosin interaction energy. Destabilizing the blocked (relaxed)-state parallels previously noted enhanced Ca2+-sensitivity conferred by these mutants. Energy landscapes also identify post-translational modifications that can rescue regulatory imbalances. For example, cardiomyopathy-associated E62Q tropomyosin mutation weakens actin-tropomyosin interaction, but phosphorylation of neighboring S61 rescues the binding-deficit, results confirmed experimentally by in vitro motility assays. Unlike results on hyper-contractility-related mutants, landscapes for tropomyosin mutants tied to hypo-contractility do not present a straightforward picture. These mutations may affect other components of the regulatory network, e.g., troponin-tropomyosin signaling.

show abstract

Cardiomyopathy-linked myosin regulatory light chain mutations disrupt myosin strain-dependent biochemistry

Cited by 79 publications

References 35 publications

The Rates of Ca2+ Dissociation and Cross-bridge Detachment from Ventricular Myofibrils as Reported by a Fluorescent Cardiac Troponin C

The Rates of Ca2+ Dissociation and Cross-bridge Detachment from Ventricular Myofibrils as Reported by a Fluorescent Cardiac Troponin C

Myosin IC generates power over a range of loads via a new tension-sensing mechanism

Energy landscapes reveal the myopathic effects of tropomyosin mutations

Contact Info

Product

Resources

About