My work focuses on Myosin Va (myoVa), which is an intracellular cargo transporter. Based on in vitro experiments, a single myoVa molecule could perform this function as it can move processively along actin tracks in a "hand-over-hand" fashion. However, this has yet to be demonstrated in vivo. The cellular context presents numerous challenges to myoVa processivity such as the dense cytoskeletal network, actin-binding proteins, and other motors that share cargo transport duties with myoVa. To study the in vivo motion and processivity of myoVa, I introduced quantum dot (Qdot) labeled myoVa molecules into cultured fibroblast (COS-7) cells by pinocytosis, and observed the motion of individual motor molecules by TIRF microscopy. I have shown that individual myoVa molecules undergo a random walk by making frequent turns onto intersecting actin filaments in the densely packed subplasmalemmal actin cortex. My current efforts are to begin to understand how myoVa is targeted to its cargo and how multiple motor molecules coordinate their activity to bring about effective cargo transport.
Faculty Highlighted Publications
Armstrong JM, Krementsova E, Michalek AJ, Heaslip AT, Nelson SR, Trybus KM, Warshaw DM. Full-length myosin Va exhibits altered gating during processive movement on actin. Proc. Natl. Acad. Sci. USA. 2012 Jan 31;109(5):E218-24.
Nelson SR, Ali MY, Warshaw DM. Quantum dot labeling strategies to characterize single-molecular motors. Methods Mol Biol. 2011;778:111-21.
Dunn AR, Kad NM, Nelson SR, Warshaw DM, Wallace SS. Single Qdot-labeled glycosylase molecules use a wedge amino acid to probe for lesions while scanning along DNA.
Nelson SR, Ali MY, Trybus KM, Warshaw DM. Random walk of processive, quantum dot-labeled myosin Va molecules within the actin cortex of COS-7 cells.