A Subdomain Interaction at the Base of the Lever Allosterically Tunes the Mechanochemical Mechanism of Myosin 5a
نویسندگان
چکیده
The motor domain of myosin is the core element performing mechanochemical energy transduction. This domain contains the actin and ATP binding sites and the base of the force-transducing lever. Coordinated subdomain movements within the motor are essential in linking the ATPase chemical cycle to translocation along actin filaments. A dynamic subdomain interface located at the base of the lever was previously shown to exert an allosteric influence on ATP hydrolysis in the non-processive myosin 2 motor. By solution kinetic, spectroscopic and ensemble and single-molecule motility experiments, we determined the role of a class-specific adaptation of this interface in the mechanochemical mechanism of myosin 5a, a processive intracellular transporter. We found that the introduction of a myosin 2-specific repulsive interaction into myosin 5a via the I67K mutation perturbs the strong-binding interaction of myosin 5a with actin, influences the mechanism of ATP binding and facilitates ATP hydrolysis. At the same time, the mutation abolishes the actin-induced activation of ADP release and, in turn, slows down processive motility, especially when myosin experiences mechanical drag exerted by the action of multiple motor molecules bound to the same actin filament. The results highlight that subtle structural adaptations of the common structural scaffold of the myosin motor enable specific allosteric tuning of motor activity shaped by widely differing physiological demands.
منابع مشابه
Melanophilin Stimulates Myosin-5a Motor Function by Allosterically Inhibiting the Interaction between the Head and Tail of Myosin-5a
The tail-inhibition model is generally accepted for the regulation of myosin-5a motor function. Inhibited myosin-5a is in a folded conformation in which its globular tail domain (GTD) interacts with its head and inhibits its motor function, and high Ca(2+) or cargo binding may reduce the interaction between the GTD and the head of myosin-5a, thus activating motor activity. Although it is well e...
متن کاملFluorescence spectra of cardiac myosin and in vivo experiment: studies on daunorubicin-induced cardiotoxicity
Objective(s):The objective of this study was to investigate the interaction of daunorubicin (DNR) and cardiac myosin (CM) and the changes in mice hearts to exhibit DNR-induced cardiotoxicity . Materials and Methods:The interaction between DNR and CM was expressed using fluorescence quenching at pH 4.0-9.0 and 15-37 °C. DNR-induced cardiotoxicity was studied using in vivo experiment. Forty grou...
متن کاملOptimization of the thread take-up lever mechanism in lockstitch sewing machine using the imperialistic competitive algorithm
متن کامل
Myosin VI dimerization triggers an unfolding of a three-helix bundle in order to extend its reach.
Myosin VI challenges the prevailing theory of how myosin motors move on actin: the lever arm hypothesis. While the reverse directionality and large powerstroke of myosin VI can be attributed to unusual properties of a subdomain of the motor (converter with a unique insert), these adaptations cannot account for the large step size on actin. Either the lever arm hypothesis needs modification, or ...
متن کاملInfluence of lever structure on myosin 5a walking.
Using electron microscopy and image processing, we have observed myosin 5a modified with lever arms of different lengths (four, six, and eight calmodulin-binding IQ domains) and orientations walking along actin filaments. Step lengths were dependent on lever length: 8IQ > 6IQ > 4IQ, which is consistent with myosin 5a having evolved to walk straight along actin. Lead heads were mostly in the pre...
متن کامل