Key result
Simultaneous observations of the head and tail domain during stepping revealed that the lever arms tilt forward in the adjacent binding state, explaining how myosin VI achieves its dual function.
Simultaneous observation of the head and tail domains of myosin VI reveals that lever arms tilt forward in the adjacent binding state, explaining its dual function as a vesicle transporter and cytoskeletal anchor.
Lever arm tilting may inform cardiac motor protein dynamics; leaves open relevance to human cardiovascular disease.
Myosin VI is an adenosine triphosphate (ATP)-driven dimeric molecular motor that has dual function as a vesicle transporter and a cytoskeletal anchor. Recently, it was reported that myosin VI generates three types of steps by taking either a distant binding or adjacent binding state (noncanonical hand-over-hand step pathway). The adjacent binding state, in which both heads bind to an actin filament near one another, is unique to myosin VI and therefore may help explain its distinct features. However, detailed information of the adjacent binding state remains unclear. Here simultaneous observations of the head and tail domain during stepping are presented. These observations show that the lever arms tilt forward in the adjacent binding state. Furthermore, it is revealed that either head could take the subsequent step with equal probability from this state. Together with previous results, a comprehensive stepping scheme is proposed; it includes the tail domain motion to explain how myosin VI achieves its dual function.
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Ikezaki et al. (2012) studied this question. Simultaneous observations of the head and tail domain during stepping revealed that the lever arms tilt forward in the adjacent binding state, explaining how myosin VI achieves its dual function.
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