HOUSTON - (Jan. 9, 2014) - Rice University researchers have engineered cells to characterize how sensitively altering the cooperative functions of motor proteins can regulate the transport of organelles.
The study, by the Rice lab of bioengineer and chemist Michael Diehl, compared the collective behaviors of kinesin-1 and myosinVa in living cells to determine how these motor proteins cooperate as they move vesicles and organelles along intracellular highways formed from cytoskeletal filaments. These transport processes are critical to numerous developmental and signaling functions within cells, and breakdowns in motor functions are also implicated in several human diseases.
The work appears this week in the Proceedings of the National Academy of Sciences.
Diehl and his colleagues at Rice's BioScience Research Collaborative, including Rice postdoctoral researchers Anand Radhakrishan and Artem Efremov and graduate student David Tsao, compared the collective responses of the motor proteins to variations in motor numbers and cargo sizes.
They began with a good understanding of the collective pulling power of kinesin motors. Kinesin is a type of protein that binds to and transports cargoes by walking along cytoskeletal filaments called "microtubules." In previous experiments, they engineered multiple motor systems that were anchored to polystyrene beads as an experimental cargo, but this time decided to engineer organelles called "peroxisomes" within living cells for these analyses.
"Our earlier work was detailed and very precise, but the central limitation was simply that the motors were not transporting a real cargo," Diehl said. In contrast to rigid beads, many organelles like peroxisomes have fluid-like lipid membranes. Motors attached to their surfaces will therefore interact in ways that are difficult to recapitulate using plastic beads.
"The physical environment inside a living cell is also diffi
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