title: Myosin VI regulates actin structure specialization through conserved cargo-binding domain sites.
abstract: Actin structures are often stable, remaining unchanged in organization for the lifetime of a differentiated cell. Little is known about stable actin structure formation, organization, or maintenance. During Drosophila spermatid individualization, long-lived actin cones mediate cellular remodeling. Myosin VI is necessary for building the dense meshwork at the cones' fronts. We test several ideas for myosin VI's mechanism of action using domain deletions or site-specific mutations of myosin VI. The head (motor) and globular tail (cargo-binding) domains were both needed for localization at the cone front and dense meshwork formation. Several conserved partner-binding sites in the globular tail previously identified in vertebrate myosin VI were critical for function in cones. Localization and promotion of proper actin organization were separable properties of myosin VI. A vertebrate myosin VI was able to localize and function, indicating that functional properties are conserved. Our data eliminate several models for myosin VI's mechanism of action and suggest its role is controlling organization and action of actin assembly regulators through interactions at conserved sites. The Drosophila orthologues of interaction partners previously identified for vertebrate myosin VI are likely not required, indicating novel partners mediate this effect. These data demonstrate that generating an organized and functional actin structure in this cell requires multiple activities coordinated by myosin VI.
authors.affiliation: Department of Biology, Washington University in St. Louis, St. Louis, Missouri, United States of America.
authors.forename: Mamiko
authors.initials: M
authors.lastname: Isaji
authors.forename: Marta
authors.initials: M
authors.lastname: Lenartowska
authors.forename: Tatsuhiko
authors.initials: T
authors.lastname: Noguchi
authors.forename: Deborah J
authors.initials: DJ
authors.lastname: Frank
authors.forename: Kathryn G
authors.initials: KG
authors.lastname: Miller
mesh_terms: D051378:Actin-Related Protein 3 / Q000378:metabolism; D000199:Actins / Q000378:metabolism* / Q000648:ultrastructure; D000595:Amino Acid Sequence; D000818:Animals; D015153:Blotting, Western; D017124:Conserved Sequence / Q000235:genetics*; D004331:Drosophila melanogaster / Q000166:cytology / Q000378:metabolism / Q000648:ultrastructure; D049452:Green Fluorescent Proteins / Q000378:metabolism; D008297:Male; D008969:Molecular Sequence Data; D050505:Mutant Proteins / Q000378:metabolism; D018995:Myosin Heavy Chains / Q000737:chemistry* / Q000378:metabolism*; D011485:Protein Binding; D015202:Protein Engineering; D017434:Protein Structure, Tertiary; D021381:Protein Transport; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D016415:Sequence Alignment; D013087:Spermatids / Q000378:metabolism; D013091:Spermatogenesis; D013329:Structure-Activity Relationship; D034421:Sus scrofa; D013737:Testis / Q000378:metabolism; D014020:Tissue Extracts; D019076:Transgenes / Q000235:genetics
chemical_list: D051378:Actin-Related Protein 3; D000199:Actins; D050505:Mutant Proteins; D011993:Recombinant Fusion Proteins; D014020:Tissue Extracts; C089785:myosin VI; D049452:Green Fluorescent Proteins; D018995:Myosin Heavy Chains