27 November 2008

Kinesin – step by step

Scientists have determined how biomotor proteins move in the cell
Maria Kostyukova, NanoNewsNet based on Nanowerk materials

Kinesin is one of the molecular motors in the cell, capable of independent movement along the filaments of the cytoskeleton (microtubules) due to the energy of splitting ATP. Kinesin performs a transport function in the cell, moving large molecules that are not capable of rapid diffusion from the center of the cell to its periphery. Research conducted at MIT has for the first time described the molecular processes in kinesin that cause its molecule to move.

A group of researchers led by Professor in the field of biomechanical engineering Matthew Lang published the results of their research on November 24, 2008 in the journal Proceedings of the National Academy of Sciences (PNAS).

Kinesin is a small transport protein, its movement along the microtubules occurs by a step mechanism. Each step occurs due to the energy of splitting of one ATP molecule and is mechanically caused by a change in the position of parts of the kinesin molecule: the bridge (shown in red) and the upper part of the molecule (shown in blue), which pass into the form of beta layers and move the protein

Since kinesin is one of the key mechanochemical systems in the cell and is actively involved in the process of cell division, understanding the features of its work can be useful in the development of therapies related to the control of cell reproduction in the body, for example, in the creation of anti-cancer drugs.

Kinesin consists of two globules that bind to a microtubule, and a long tail part to which molecules are attached to transport from one part of the cell to another. Globules can rotate and "walk" along the microtubule, and at a surprisingly high speed on a cellular scale – 100 steps (800 nanometers) per second.

In their work, Professor Lang and his colleagues drew attention to the experimental confirmation of data on the structure of kinesin, published in January 2008 in the journal Structure. In this work, it was also assumed, and now confirmed experimentally, that there is a small section of the molecule that gives a signal for the globules and the tail of the molecule to move, and that this is an energy signal. The two subunits of the protein – its N-terminal part and the bridge – become linear, and then fold in such a way that the kinesin globule moves one step along the microtubule.

Further plans to study this interesting mechanism of molecular movement are to find out how two kinesin globules coordinate their "steps".

Studies of the structure and functional activity of kinesin are funded by the National Institutes of Health (NIH), as well as the Army Research Office Institute.

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