Dissection of the Ascaris sperm motility machinery identifies key proteins involved in major sperm protein-based amoeboid locomotion

Although Ascaris sperm motility closely resembles that seen in many other types of crawling cells, the lamellipodial dynamics that drive movement result from modulation of a cytoskeleton based on the major sperm protein (MSP) rather than actin. The dynamics of the Ascaris sperm cytoskeleton can be s...

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Bibliographic Details
Published in:Molecular biology of the cell 2003-12, Vol.14 (12), p.5082-5088
Main Authors: Buttery, Shawnna M, Ekman, Gail C, Seavy, Margaret, Stewart, Murray, Roberts, Thomas M
Format: Article
Language:English
Subjects:
Amino Acid Sequence
Animals
Ascaris - metabolism
Ascaris - physiology
Cytoskeleton - metabolism
Cytoskeleton - physiology
Helminth Proteins - metabolism
Helminth Proteins - physiology
Intestines - microbiology
Locomotion - physiology
Male
Molecular Sequence Data
Pseudopodia - metabolism
Pseudopodia - physiology
Sequence Homology, Amino Acid
Sperm Motility - physiology
Spermatozoa - metabolism
Spermatozoa - physiology
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Summary:Although Ascaris sperm motility closely resembles that seen in many other types of crawling cells, the lamellipodial dynamics that drive movement result from modulation of a cytoskeleton based on the major sperm protein (MSP) rather than actin. The dynamics of the Ascaris sperm cytoskeleton can be studied in a cell-free in vitro system based on the movement of plasma membrane vesicles by fibers constructed from bundles of MSP filaments. In addition to ATP, MSP, and a plasma membrane protein, reconstitution of MSP motility in this cell-free extract requires cytosolic proteins that orchestrate the site-specific assembly and bundling of MSP filaments that generates locomotion. Here, we identify a fraction of cytosol that is comprised of a small number of proteins but contains all of the soluble components required to assemble fibers. We have purified two of these proteins, designated MSP fiber proteins (MFPs) 1 and 2 and demonstrated by immunolabeling that both are located in the MSP cytoskeleton in cells and in fibers. These proteins had reciprocal effects on fiber assembly in vitro: MFP1 decreased the rate of fiber growth, whereas MFP2 increased the growth rate.
ISSN:1059-1524
1939-4586
DOI:10.1091/mbc.E03-04-0246