Mohshin Quraishi, M.Phil fellow - SINGLE MOLECULE MYOSIN

A Brief Study of Single Molecule Myosin

Single molecule study is very difficult as its size is very tiny (~10^-8meter)and their ATpase cycle occur on the milisecond time scale.Making measurement with large number of molecule also problamatic, because the discrete actions excecuted by individuals molecules become 'blurred' when the net output from large groups of asynchronous motors is monitored.But many sophisticated technique and instrument have been develop to study a single molecule. After discovering ‘optical tweezers’ single molecule studies have became very popular. Optical tweezers (or optical traps) are powerful tools for manipulating microscopic objects. They can also be used to measure forces acting on these particles.

Myosin V is a two-legged molecular motor is considered to walk with its two legs like a human. Its step size was known to be 36 nm, the pitch of the helical actin filament.From this spiral motion of myosin V, M.Yusuf Ali group found that myosin V positions and orients the unbounds head such that the head will land at the 11th or 13th actin sub unit on the opposing stand of the actin double helix.Myosin V would walk straight along actin filament if myosin head lands on 13th subunit and the step size would be ~36 nm. However, 36 nm is the helical repeat length of actin.Myosin V rotates around the actin filament as a left handed screw meaning is that it makes 6° left - handed rotation per step with respect to the axis of actin filament.

My past work on –single molecule studies of the mechanism of myosin molecular motors will undoubtedlyChange or improve our fundamental thinking on the role of the myosin and their involvement in different diseases.

Due to the extremely limited fund, reagents and other materials I had to work hard to complete my thesis.

In future, if I have any opportunity with new technologies, I will be able to proceed my work:

To develop the technology and analysis to motile systems further so that definite values of force and step length can be obtained at a high resolution
To obtained as details as possible three dimensional solutions, at time resolution, of X-ray diffraction data that can be obtained from intact muscle during mechanical transients.
Try to find a way to understand quantitatively the detailed internal structural mechanics and energy generation of myosin head and actin interacting with ATP.

New Scientist

Physics World

To develop the technology and analysis to motile systems further so that definite values of force and step length can be obtained at a high resolution

To obtained as details as possible three dimensional solutions, at time resolution, of X-ray diffraction data that can be obtained from intact muscle during mechanical transients.

Try to find a way to understand quantitatively the detailed internal structural mechanics and energy generation of myosin head and actin interacting with ATP.