Two kinds of kinesin molecular motors have different properties of coordination, Kyoto University’s School of Engineering has found. The findings were made possible thanks to a new tool the team developed that parks individual motors on platforms thousands of times smaller than a single cell.
“Kinesin is a motor protein that is involved in actions such as cell division, muscle contractions, and flagella movement. They move along these long protein filaments called microtubules. In the body, kinesins work as a team to transport large molecules inside a cell, or allow the cell itself to move,”
explains first author Taikopaul Kaneko.
Molecular Motors
Body movement, from the muscles in your arms to the neurons transporting those signals to your brain, relies on a massive collection of proteins called molecular motors. Molecular motors are proteins that convert chemical energy into mechanical movement, and have different functions depending on their task.
However, because they are so small, the exact mechanisms by which these molecules coordinate with each other is poorly understood.
The researchers evaluated two kinesins: kinesin-1 and kinesin-14, which are involved in intercellular transport and cell division, respectively. Their results showed that in the case of kinesin-1, neither the number nor spacing of the molecules change the transport velocity of microtubules.
In contrast, kinesin-14 decreased transport velocity as the number of motors on a filament increased, but increased as the spacing of the motors increased. The results indicate that while kinesin-1 molecules work independently, kinesin-14 interacts with each other to tune the speed of transport.
Velocity Of Microtubules
The microtubule velocity was found to be independent of the number of kinesin-1 motors in the range of 3 to 30 motors and spacing of the kinesin-1 motors. In contrast, the velocity decreased within the range of 3 to 10 kinesin-14 motors and reached a plateau of over 10 motors.
Ryuji Yokokawa who led the team was surprised by the results;
“Before we started this study, we thought that more motors led to faster transport and more force. But like most things in biology, it’s rarely that simple.”
The team will be using their new nano-patterning method to study the mechanics of other kinesins and different molecular motors.
“Humans have over 40 kinesins along with two other types of molecular motors called myosin and dynein. We can even modify our array to study how these motors act in a density gradient. Our results and this new tool are sure to expand our understanding of the various basic cellular processes fundamental to all life,”
concludes Yokokawa.
Original Study: Different motilities of microtubules driven by kinesin-1 and kinesin-14 motors patterned on nanopillars
Image credit: Science Graphics
