Biophysics Program, University of Michigan, Ann Arbor, United States
Guido Scarabelli
Department of Computational Medicine and Bioinformatics, University of Michigan, Ann Arbor, United States
Barry J Grant
Division of Biological Sciences, Section of Molecular Biology, University of California, San Diego, San Diego, United States
David Sept
Biophysics Program, University of Michigan, Ann Arbor, United States; Department of Biomedical Engineering, University of Michigan, Ann Arbor, United States; Center for Computational Medicine and Bioinformatics, University of Michigan, Ann Arbor, United States
Matthew J Lang
Department of Chemical and Biomolecular Engineering, Vanderbilt University, Nashville, United States; Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, United States
Cellular and Molecular Biology Program, University of Michigan, Ann Arbor, United States; Biophysics Program, University of Michigan, Ann Arbor, United States; Department of Cell and Developmental Biology, University of Michigan Medical School, Ann Arbor, United States
Kinesin force generation involves ATP-induced docking of the neck linker (NL) along the motor core. However, the roles of the proposed steps of NL docking, cover-neck bundle (CNB) and asparagine latch (N-latch) formation, during force generation are unclear. Furthermore, the necessity of NL docking for transport of membrane-bound cargo in cells has not been tested. We generated kinesin-1 motors impaired in CNB and/or N-latch formation based on molecular dynamics simulations. The mutant motors displayed reduced force output and inability to stall in optical trap assays but exhibited increased speeds, run lengths, and landing rates under unloaded conditions. NL docking thus enhances force production but at a cost to speed and processivity. In cells, teams of mutant motors were hindered in their ability to drive transport of Golgi elements (high-load cargo) but not peroxisomes (low-load cargo). These results demonstrate that the NL serves as a mechanical element for kinesin-1 transport under physiological conditions.
