Read Examining Kinesin Motor Family Diversity: A Mechanistic Study of Ncd and OSM-3 Motor Proteins

Examining Kinesin Motor Family Diversity: A Mechanistic Study of Ncd and OSM-3 Motor Proteins

Nicholas F. Endres

4.9/5 (24976 ratings)

Description:Kinesin motor proteins produce motion and force along microtubules and are essential for the organization of subcellular components (Vale, 2003). The kinesin superfamily is divided into 14 subfamilies that carry out a variety of biological functions (Miki et al., 2005). In spite of their diversity, Kinesin motors all share a conserved catalytic domain that binds to microtubule and hydrolyzes ATP (Vale and Milligan, 2000). The two studies presented here are examples of how kinesin motors can be uniquely adapted to perform their specific cellular functions. The first study focuses on the Kinesin-14 family member Ncd. Most kinesin motors, exemplified by Kinesin-1, move towards the microtubule plus end, and the structural changes that govern this directional preference have been described (Rice et al., 1999). In contrast, the structural changes underlying the minus-end-directed motility of Kinesin-14 motors are less well understood. Using cryo-electron microscopy, we demonstrate that a coiled-coil mechanical element of microtubule-bound Ncd rotates ∼70° towards the minus end upon ATP binding. Extending or shortening this coiled coil increases or decreases velocity, respectively, without affecting ATPase activity. Our results show that the force-producing conformational change in Ncd occurs on ATP binding, as in other kinesins, but involves the swing of a lever-arm mechanical element similar to that described for myosins. The second study focuses on OSM-3, a Kinesin-2 family member involved in intraflagellar transport (IFT) (Scholey et al., 2004). Here, using a single molecule fluorescence assay, we show that bacterially-expressed OSM-3 GFP does not move processively (multiple steps along a microtubule without dissociation). However, a single point mutation in a predicted hinge region of the OSM-3 coiled-coil stalk, as well as a deletion of that hinge, activates robust processive movement of OSM-3. The processivity of wild-type OSM-3 also can be activated by attaching the motor to beads in an optical trap. Sucrose gradient analysis reveals that OSM-3 adopts a compact conformation that becomes extended in the hinge mutants or at high salt. We propose that the processivity of OSM-3 is repressed by an intramolecular interaction in vivo that can be relieved by IFT cargo binding.We have made it easy for you to find a PDF Ebooks without any digging. And by having access to our ebooks online or by storing it on your computer, you have convenient answers with Examining Kinesin Motor Family Diversity: A Mechanistic Study of Ncd and OSM-3 Motor Proteins. To get started finding Examining Kinesin Motor Family Diversity: A Mechanistic Study of Ncd and OSM-3 Motor Proteins, you are right to find our website which has a comprehensive collection of manuals listed.
Our library is the biggest of these that have literally hundreds of thousands of different products represented.

Pages: 190

Format: PDF, EPUB & Kindle Edition

Publisher: —

Release: 2006

ISBN: hZy9JbXwh0IC

Description: Kinesin motor proteins produce motion and force along microtubules and are essential for the organization of subcellular components (Vale, 2003). The kinesin superfamily is divided into 14 subfamilies that carry out a variety of biological functions (Miki et al., 2005). In spite of their diversity, Kinesin motors all share a conserved catalytic domain that binds to microtubule and hydrolyzes ATP (Vale and Milligan, 2000). The two studies presented here are examples of how kinesin motors can be uniquely adapted to perform their specific cellular functions. The first study focuses on the Kinesin-14 family member Ncd. Most kinesin motors, exemplified by Kinesin-1, move towards the microtubule plus end, and the structural changes that govern this directional preference have been described (Rice et al., 1999). In contrast, the structural changes underlying the minus-end-directed motility of Kinesin-14 motors are less well understood. Using cryo-electron microscopy, we demonstrate that a coiled-coil mechanical element of microtubule-bound Ncd rotates ∼70° towards the minus end upon ATP binding. Extending or shortening this coiled coil increases or decreases velocity, respectively, without affecting ATPase activity. Our results show that the force-producing conformational change in Ncd occurs on ATP binding, as in other kinesins, but involves the swing of a lever-arm mechanical element similar to that described for myosins. The second study focuses on OSM-3, a Kinesin-2 family member involved in intraflagellar transport (IFT) (Scholey et al., 2004). Here, using a single molecule fluorescence assay, we show that bacterially-expressed OSM-3 GFP does not move processively (multiple steps along a microtubule without dissociation). However, a single point mutation in a predicted hinge region of the OSM-3 coiled-coil stalk, as well as a deletion of that hinge, activates robust processive movement of OSM-3. The processivity of wild-type OSM-3 also can be activated by attaching the motor to beads in an optical trap. Sucrose gradient analysis reveals that OSM-3 adopts a compact conformation that becomes extended in the hinge mutants or at high salt. We propose that the processivity of OSM-3 is repressed by an intramolecular interaction in vivo that can be relieved by IFT cargo binding.We have made it easy for you to find a PDF Ebooks without any digging. And by having access to our ebooks online or by storing it on your computer, you have convenient answers with Examining Kinesin Motor Family Diversity: A Mechanistic Study of Ncd and OSM-3 Motor Proteins. To get started finding Examining Kinesin Motor Family Diversity: A Mechanistic Study of Ncd and OSM-3 Motor Proteins, you are right to find our website which has a comprehensive collection of manuals listed.
Our library is the biggest of these that have literally hundreds of thousands of different products represented.

Special Offer | $0.00

Special Offer! | $0.00

Examining Kinesin Motor Family Diversity: A Mechanistic Study of Ncd and OSM-3 Motor Proteins

Examining Kinesin Motor Family Diversity: A Mechanistic Study of Ncd and OSM-3 Motor Proteins

More Books

Science Magazine's State of the Planet 2008-2009: with a Special Section on Energy and Sustainability

Science Magazine's State of the Planet 2008-2009: with a Special Section on Energy and Sustainability