Atsuko Hikikoshi Iwane

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Actomyosin, a complex of actin filaments and myosin motor proteins, is responsible for force generation during muscle contraction. To resolve the individual mechanical events of force generation by actomyosin, we have developed a new instrument with which we can capture and directly manipulate individual myosin subfragment-1 molecules using a scanning(More)
F-actin is a helical assembly of actin, which is a component of muscle fibres essential for contraction and has a crucial role in numerous cellular processes, such as the formation of lamellipodia and filopodia, as the most abundant component and regulator of cytoskeletons by dynamic assembly and disassembly (from G-actin to F-actin and vice versa). Actin(More)
Myosin VI is a two-headed molecular motor that moves along an actin filament in the direction opposite to most other myosins. Previously, a single myosin VI molecule has been shown to proceed with steps that are large compared to its neck size: either it walks by somehow extending its neck or one head slides along actin for a long distance before the other(More)
The cargo transporter myosin-VI processively walks along actin filaments using its two heads. Here we use single-molecule nanometry to show that the strong binding by myosin heads to actin is greatly accelerated (approximately 30-fold) when backward strain is applied to weakly bound heads during the actin search. We propose that the myosin head searches for(More)
To investigate the role of the neck domain of kinesin, we used optical trapping nanometry to perform high-resolution measurements of the movements and forces produced by recombinant kinesin fragments in which the neck domains were shortened or replaced by an artificial random coil. Truncated kinesin fragments (K351) that contain a motor domain consisting of(More)
Class VI myosin is an intracellular vesicle and organelle transporter that moves along actin filaments in a direction opposite to most other known myosin classes. The myosin-VI was expected to form a dimer to move processively along actin filaments with a hand-over-hand mechanism like other myosin organelle transporters. Recently, however, wild-type(More)
Class-V myosin proceeds along actin filaments with large ( approximately 36 nm) steps. Myosin-V has two heads, each of which consists of a motor domain and a long (23 nm) neck domain. In accordance with the widely accepted lever-arm model, it was suggested that myosin-V steps to successive (36 nm) target zones along the actin helical repeat by tilting its(More)
We have previously measured the process of displacement generation by a single head of muscle myosin (S1) using scanning probe nanometry. Given that the myosin head was rigidly attached to a fairly large scanning probe, it was assumed to stably interact with an underlying actin filament without diffusing away as would be the case in muscle. The myosin head(More)
Lissencephaly is a devastating neurological disorder caused by defective neuronal migration. The LIS1 (or PAFAH1B1) gene was identified as the gene mutated in lissencephaly patients, and was found to regulate cytoplasmic dynein function and localization. In particular, LIS1 is essential for anterograde transport of cytoplasmic dynein as a part of the(More)
It is widely accepted that the vesicle-transporter myosin-V moves processively along F-actin with large steps of approximately 36 nm using a hand-over-hand mechanism. A key question is how does the rear head of two-headed myosin-V search for the forward actin target in the forward direction. Scanning probe nanometry was used to resolve this underlying(More)