Final Report Summary - RMPSHSSI (REVEALING MYOSIN'S POWER STROKE WITH HIGH-SPEED SCATTERING INTERFEROMETRY) Molecular motors are remarkable nanoscopic machines that are responsible for most forms of movement we encounter in the cellular world. One of their major roles relates to transport inside cells, which are highly organized and divided into many parts of different functions. This implies that cellular transport is required for efficient cellular function.In this work we visualized the movement of one of such proteins – myosin 5. One could think of myosin 5 as a small lorry, which can move remarkably long distances while caring a cargo. Remarkably, this protein resembles like a two legged creature that makes nanoscale steps. We used very small gold particles, smaller than myosin itself to label this protein. Myosin together with such a“gold tag” could be detected and its motion was recorded using a new microscopy technique called iSCAT (Interferometric Scattering Microscopy). iSCAT allowed us to ‘see’ the tiny steps of this motor; tens of nanometres small at up to 1000 frames per second. The results provided the first experimental evidence that this family of motor proteins take regular ‘stiff-legged’ steps. The findings are interesting to anyone trying to understand how the cellular machinery works, but it is also likely to be very important for those looking to build nanomachines. The capabilities of iSCAT for fast and very sensitive imaging have already attracted attention of several scientific groups working on different motors (kinesins and dyneins). With this new tool we can hope to understand how motor proteins work facilitating not only cellular transport but also cell division, cell replication or cell communication.
