Molecular Motors Cooperate in Moving Cellular Cargo

University of Illinois at Urbana-Champaign researchers – using an extremely fast and accurate imaging technique – have shed light on the tiny movements of molecular motors that shuttle material within living cells. The motors cooperate in a delicate choreography of steps, rather than engaging in the brute-force tug of war many scientists had imagined.

The researchers discovered that two molecular motors – dynein and kinesin – do not compete for control, even though they want to move the same cargo in opposite directions Dynein and kinesin are biomolecular motors that haul cargo from one part of a cell to another. Dynein moves material from the cell membrane to the nucleus; kinesin moves material from the cell nucleus to the cell membrane. The little cargo transporters accomplish their task by stepping along filaments called microtubules.

To measure such minuscule motion, the researchers developed a technique called Fluorescence Imaging with One Nanometer Accuracy (FIONA). The technique can locate a fluorescent dye to within 1.5 nm. Recent improvements to FIONA now allow scientists to detect motion with millisecond time resolution.

The team used FIONA to track fluorescently-labeled peroxisomes (organelles that break down toxic substances) inside specially cultured fruit fly cells. This was the first time the imaging technique had been used inside a living cell.

The researchers also noted that faster movements occurred with the same step size, but with greater rapidity. When measured outside the cell, kinesin moved about 0.5 micron per second. Inside the cell, the speed increased to 12 microns per second.

Find out more at: www.mrl.uiuc.edu