title: Spire contains actin binding domains and is related to ascidian posterior end mark-5.
abstract: Spire is a maternal effect locus that affects both the dorsal-ventral and anterior-posterior axes of the Drosophila egg and embryo. It is required for localization of determinants within the developing oocyte to the posterior pole and to the dorsal anterior corner. During mid-oogenesis, spire mutants display premature microtubule-dependent cytoplasmic streaming, a phenotype that can be mimicked by pharmacological disruption of the actin cytoskeleton with cytochalasin D. Spire has been cloned by transposon tagging and is related to posterior end mark-5, a gene from sea squirts that encodes a posteriorly localized mRNA. Spire mRNA is not, however, localized to the posterior pole. SPIRE also contains two domains with similarity to the actin monomer-binding WH2 domain, and we demonstrate that SPIRE binds to actin in the interaction trap system and in vitro. In addition, SPIRE interacts with the rho family GTPases RHOA, RAC1 and CDC42 in the interaction trap system. Thus, our evidence supports the model that SPIRE links rho family signaling to the actin cytoskeleton.
authors.affiliation: Department of Molecular and Cellular Biology, Interdisciplinary Program in Genetics, University of Arizona, Tucson, AZ 85721, USA.
authors.forename: A
authors.initials: A
authors.lastname: Wellington
authors.forename: S
authors.initials: S
authors.lastname: Emmons
authors.forename: B
authors.initials: B
authors.lastname: James
authors.forename: J
authors.initials: J
authors.lastname: Calley
authors.forename: M
authors.initials: M
authors.lastname: Grover
authors.forename: P
authors.initials: P
authors.lastname: Tolias
authors.forename: L
authors.initials: L
authors.lastname: Manseau
mesh_terms: D000199:Actins / Q000235:genetics / Q000378:metabolism*; D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites; D003001:Cloning, Molecular; D015638:Cytochalasin D / Q000494:pharmacology; D003599:Cytoskeleton / Q000187:drug effects / Q000378:metabolism; D004330:Drosophila / Q000196:embryology / Q000235:genetics*; D029721:Drosophila Proteins; D004527:Egg Proteins / Q000235:genetics; D004625:Embryo, Nonmammalian / Q000187:drug effects; D018507:Gene Expression Regulation, Developmental; D008840:Microfilament Proteins / Q000187:drug effects / Q000235:genetics* / Q000378:metabolism; D008969:Molecular Sequence Data; D019384:Nucleic Acid Synthesis Inhibitors / Q000494:pharmacology; D010641:Phenotype; D017386:Sequence Homology, Amino Acid; D014561:Urochordata / Q000235:genetics; D020764:cdc42 GTP-Binding Protein / Q000235:genetics / Q000378:metabolism; D020830:rac1 GTP-Binding Protein / Q000235:genetics / Q000378:metabolism; D020742:rhoA GTP-Binding Protein / Q000235:genetics / Q000378:metabolism
chemical_list: D000199:Actins; D029721:Drosophila Proteins; D004527:Egg Proteins; D008840:Microfilament Proteins; D019384:Nucleic Acid Synthesis Inhibitors; C110210:PEM-5 protein, Ciona savignyi; C402385:spir protein, Drosophila; D015638:Cytochalasin D; D020764:cdc42 GTP-Binding Protein; D020830:rac1 GTP-Binding Protein; D020742:rhoA GTP-Binding Protein