title: The role of filament-packing dynamics in powering amoeboid cell motility.
abstract: Although several models have been proposed to account for how cytoskeleton polymerization drives protrusion in cell motility, the precise mechanism remains controversial. Here, we show that, in addition to force exerted directly against the membrane by growing filaments, the way elongating filaments pack also contributes to protrusion by generating an expansion of the cytoskeleton gel. Tomography shows that filament packing in the major sperm protein (MSP) -based nematode sperm-motility machinery resembles that observed with rigid rods. Maximum rod-packing density decreases dramatically as the rods lengthen. Therefore, as filaments elongate, the cytoskeleton gel expands to accommodate their packing less densely. This volume expansion combines with polymerization to drive protrusion. Consistent with this hypothesis, an engineered MSP mutant that generates shorter filaments shows higher filament-packing density and slower movement.
authors.affiliation: Department of Biological Science and Institute of Molecular Biophysics, Florida State University, Tallahassee, FL 32306, USA.
authors.forename: Long
authors.initials: L
authors.lastname: Miao
authors.forename: Orion
authors.initials: O
authors.lastname: Vanderlinde
authors.forename: Jun
authors.initials: J
authors.lastname: Liu
authors.forename: Richard P
authors.initials: RP
authors.lastname: Grant
authors.forename: Alan
authors.initials: A
authors.lastname: Wouterse
authors.forename: Katsuya
authors.initials: K
authors.lastname: Shimabukuro
authors.forename: Albert
authors.initials: A
authors.lastname: Philipse
authors.forename: Murray
authors.initials: M
authors.lastname: Stewart
authors.forename: Thomas M
authors.initials: TM
authors.lastname: Roberts
mesh_terms: D008841:Actin Cytoskeleton / Q000378:metabolism; D000818:Animals; D017165:Ascaris suum / Q000502:physiology*; D003599:Cytoskeleton / Q000378:metabolism*; D015801:Helminth Proteins / Q000235:genetics / Q000378:metabolism*; D020409:Molecular Motor Proteins; D009068:Movement; D050505:Mutant Proteins; D014054:Tomography
chemical_list: D015801:Helminth Proteins; D020409:Molecular Motor Proteins; D050505:Mutant Proteins; C050602:major sperm protein, nematode