The effect of nucleotide upon a specific isomerization of actomyosin subfragment 1

Geeves, Michael A.; Jeffries, Tracy E.

doi:10.1042/bj2560041

Cited by 57 publications

(56 citation statements)

References 17 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Because gating is achieved by preventing ATP-induced dissociation of the lead head from actin, we examined the im- pact of leucine 310 on ATP-induced actin dissociation. This involved determining the rate of transition from strong to weak actin binding (K 1 Ј k ϩ2 Ј ), as monitored by pyrene actin fluorescence (23). As shown in Table 1, removal of insert-1 increases the rate of ATP-induced dissociation by 10-fold, consistent with our earlier reports (3,12).…”

Section: Resultssupporting

confidence: 85%

Role of Insert-1 of Myosin VI in Modulating Nucleotide Affinity

Pylypenko

Song

Squires

et al. 2011

Journal of Biological Chemistry

View full text Add to dashboard Cite

Myosin VI is unique in its directionality among myosin superfamily members and also displays a slow and strain-dependent rate of ATP binding that allows for gating between its heads. In this study we demonstrate that leucine 310 is positioned by a class VI-specific insert, insert-1, so as to account for the selective hindrance of ATP versus ADP binding. Mutation of leucine 310 to glycine removes all influence of insert-1 on ATP binding. Furthermore, by analyzing myosin VI structures with either leucine 310 substituted to a glycine or complete removal of insert-1, we conclude that nucleotides may initially bind to myosin by their purine rings before docking their phosphate moieties. Otherwise, insert-1 could not exert a differential influence on ATP versus ADP binding.Myosin VI is the only myosin superfamily member that has been shown to traffic toward the minus (pointed) end of actin filaments (1). This unique directionality is made possible due to a myosin VI class-specific structural element that is known as insert-2 and enables myosin VI to perform unique cellular functions (2). This insert wraps around the myosin VI converter and binds a calmodulin via an unusual calmodulin binding motif (3). This redirects the lever arm of myosin VI ϳ120°as compared with plus-end-directed myosin motors.Like myosin V, dimeric myosin VI can function as a processive motor on actin (4 -7). That is to say that the dimer can move along actin in a hand-over-hand fashion with steps of 30 -36 nm. As in the case of the plus-end directed processive dimer of myosin Va (8 -11), the processive movement of myosin VI is optimized by "gating" between the heads. Intramolecular strain stalls the lead head until the rear head has detached from actin as the dimer moves along the filament (8 -12). However, the mechanism of how this is accomplished differs between myosin V and VI, necessitated by their opposite directionalities. In the case of myosin V, intramolecular strain greatly decreases the rate of dissociation of MgADP from the lead head (8 -11), whereas in the case of myosin VI, ADP dissociation is unaffected, but ATP binding is greatly slowed on the lead head, preventing its detachment (12). This is illustrated in Fig. 1.Based on the structure of myosin VI (3), it appeared that another myosin VI class-specific insert, insert-1, is responsible for impeding ATP binding. Indeed, even in the absence of strain, binding of ATP to monomeric myosin VI is at least an order of magnitude slower than binding to myosin V (3), and removal of the 26-residue insert increased the rate of ATP binding (3, 12). The mechanism of how this is achieved was not entirely clear, although we postulated that insert-1 positioned the side chain of leucine 310 physically in the way so that it impeded ATP but not ADP entry into the pocket.In this study we examine if positioning of leucine 310 does indeed provide steric hindrance for ATP binding and is in fact the mechanism by which myosin VI gating is achieved. Although we have examined the effects of insert-1 on nucleo...

show abstract

Section: Resultssupporting

confidence: 85%

Role of Insert-1 of Myosin VI in Modulating Nucleotide Affinity

Pylypenko

Song

Squires

et al. 2011

Journal of Biological Chemistry

View full text Add to dashboard Cite

show abstract

“…The binding of S1 to pyr-actin results in a 60-70% quenching ofthe pyrene fluorescence (12,13) and provides a monitor of this interaction. A titration of 0.5 ,uM pyr-actin with MHF at low ionic strength (30 mM) shows that MHF binds to pyr-actin and quenches the fluorescence by 80%6, somewhat greater quenching than that observed for rabbit skeletal S1.…”

Section: Resultsmentioning

confidence: 99%

Kinetic characterization of a cytoplasmic myosin motor domain expressed in Dictyostelium discoideum.

Ritchie

Geeves

Woodward

et al. 1993

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

Self Cite

102

View full text Add to dashboard Cite

show abstract

“…3). This dissociation was monitored by the increase in the pyrene fluorescence labeled on actin (36). The mean K 1 k ؉2 value from four different MD preparations was 4.1 Ϯ 0.1 M Ϫ1 s Ϫ1 .…”

Section: Kinetic Analysismentioning

confidence: 99%

Kinetic Mechanism of the Fastest Motor Protein, Chara Myosin

Ito

Ikebe

Kashiyama

et al. 2007

Journal of Biological Chemistry

View full text Add to dashboard Cite

Chara corallina class XI myosin is by far the fastest molecular motor. To investigate the molecular mechanism of this fast movement, we performed a kinetic analysis of a recombinant motor domain of Chara myosin. We estimated the time spent in the strongly bound state with actin by measuring rate constants of ADP dissociation from actin⅐motor domain complex and ATP-induced dissociation of the motor domain from actin. The rate constant of ADP dissociation from acto-motor domain was >2800 s ؊1 , and the rate constant of ATP-induced dissociation of the motor domain from actin at physiological ATP concentration was 2200 s ؊1 . From these data, the time spent in the strongly bound state with actin was estimated to be <0.82 ms. This value is the shortest among known values for various myosins and yields the duty ratio of <0.3 with a V max value of the actin-activated ATPase activity of 390 s ؊1 . The addition of the long neck domain of myosin Va to the Chara motor domain largely increased the velocity of the motility without increasing the ATP hydrolysis cycle rate, consistent with the swinging lever model. In addition, this study reveals some striking kinetic features of Chara myosin that are suited for the fast movement: a dramatic acceleration of ADP release by actin (1000-fold) and extremely fast ATP binding rate.Myosin is an actin-based motor protein that converts chemical energy liberated by the ATP hydrolysis into directed movement of actin filaments. Phylogenetic analysis of myosin sequences revealed that there are at least 24 classes of myosin (1). Motor functions, such as motility and ATP hydrolysis activity, vary significantly among these classes of myosin. Among those known so far, myosin from alga Chara corallina is the fastest, moving actin filaments at 40 -60 m/s in the in vitro motility assay (2-4). This velocity is ϳ10 times faster than that of the fast skeletal muscle myosin (5). We have been interested in the mechanism how this plant myosin can move so fast. To understand the molecular mechanism of the fast movement,

show abstract

The effect of nucleotide upon a specific isomerization of actomyosin subfragment 1

Cited by 57 publications

References 17 publications

Role of Insert-1 of Myosin VI in Modulating Nucleotide Affinity

Role of Insert-1 of Myosin VI in Modulating Nucleotide Affinity

Kinetic characterization of a cytoplasmic myosin motor domain expressed in Dictyostelium discoideum.

Kinetic Mechanism of the Fastest Motor Protein, Chara Myosin

Contact Info

Product

Resources

About