Abstract
The dynamics of the cytoskeleton are largely driven by cytoskeletal motor proteins. Complex cellular functions, such as mitotsis, need a high degree of control of these motors. The versatility and sophistication of biological nanomachines still challenges our understanding. Kinesin-5 motors fulfill
essential roles in mitotic spindle morphogenesis and dynamics and were thought to be slow, processive microtubule (MT)-plus-end directed motors. Here we have examined in vitro and in vivo functions of the Saccharomyces assays and single-molecule fluorescence microscopy. In vivo, the majority of Cin8 motors moved slowly towards MT plus-ends, but we also observed occasional minus-end directed motility episodes. In vitro, individual Cin8 motors could be switched by ionic conditions from rapid (up to 50 lm/min) and processive minus-end, to bidirectional, to slow plus-end motion. Deletion of the uniquely large insert in loop 8 of Cin8 induced bias towards minus-end motility and
strongly affected the directional switching of Cin8 both in vivo and in vitro. The entirely unexpected in vivo and in vitro switching of Cin8 directionality and speed demonstrate that kinesins are much more complex than thought. These results will force us to rethink molecular models of motor function and will move the regulation of motors into the limelight as pivotal for understanding cytoskeleton-based machineries.
essential roles in mitotic spindle morphogenesis and dynamics and were thought to be slow, processive microtubule (MT)-plus-end directed motors. Here we have examined in vitro and in vivo functions of the Saccharomyces assays and single-molecule fluorescence microscopy. In vivo, the majority of Cin8 motors moved slowly towards MT plus-ends, but we also observed occasional minus-end directed motility episodes. In vitro, individual Cin8 motors could be switched by ionic conditions from rapid (up to 50 lm/min) and processive minus-end, to bidirectional, to slow plus-end motion. Deletion of the uniquely large insert in loop 8 of Cin8 induced bias towards minus-end motility and
strongly affected the directional switching of Cin8 both in vivo and in vitro. The entirely unexpected in vivo and in vitro switching of Cin8 directionality and speed demonstrate that kinesins are much more complex than thought. These results will force us to rethink molecular models of motor function and will move the regulation of motors into the limelight as pivotal for understanding cytoskeleton-based machineries.
| Original language | English |
|---|---|
| Pages (from-to) | 163-163 |
| Journal | European Biophysics Journal |
| Volume | 40 |
| State | Published - Aug 2011 |