Researchers have for the first time shown how the world's smallest moving machines generate the motion needed to transport their chemical cargo throughout cells. The discovery of how one tiny component of the motor protein kinesin powers its movement represents an important insight into one of the most fundamental aspects of biology.
"All cells are churning with internal motion, which involves transport of materials from one place in the cell to another," said Howard Hughes Medical Institute investigator Ronald Vale of the University of California, San Francisco. "It's like trafficking goods within a city. These goods include chromosomes during cell division, and transport of membranes or proteins within cells.
"The kinesin motors responsible for this transport are the world's smallest moving machines, even the smallest in the protein world," he said. "So, besides their biological significance, it's exciting to understand how these very compact machines -- many orders of magnitude smaller than anything humans have produced -- have evolved that ability to generate motion."
Basically, the kinesin protein links with another kinesin to form a two-molecule ferry that moves cellular cargo along tram tracks composed of infinitesimal filaments called microtubules that criss-cross the cell's interior.
In the December 16, 1999, issue of the journal Nature, Vale and his colleagues describe how they analyzed the motion of individual kinesin molecules, ultimately pinpointing the portion of the kinesin protein responsible for generating movement.
The researchers' analyses showed that a tiny piece of the kinesin protein dubbed the "neck
linker" abruptly stiffens like Velcro® zipping up when the energy molecule ATP attaches
to kinesin. This stiffening throws the neck linker forward and provides the mechanical force that puts
the kinesin molecule in mo
Contact: Jim Keeley
Howard Hughes Medical Institute