title: Drosophila Cappuccino alleles provide insight into formin mechanism and role in oogenesis.
abstract: During Drosophila development, the formin actin nucleator Cappuccino (Capu) helps build a cytoplasmic actin mesh throughout the oocyte. Loss of Capu leads to female sterility, presumably because polarity determinants fail to localize properly in the absence of the mesh. To gain deeper insight into how Capu builds this actin mesh, we systematically characterized seven capu alleles, which have missense mutations in Capu's formin homology 2 (FH2) domain. We report that all seven alleles have deleterious effects on fly fertility and the actin mesh in vivo but have strikingly different effects on Capu's biochemical activity in vitro. Using a combination of bulk and single- filament actin-assembly assays, we find that the alleles differentially affect Capu's ability to nucleate and processively elongate actin filaments. We also identify a unique "loop" in the lasso region of Capu's FH2 domain. Removing this loop enhances Capu's nucleation, elongation, and F-actin-bundling activities in vitro. Together our results on the loop and the seven missense mutations provides mechanistic insight into formin function in general and Capu's role in the Drosophila oocyte in particular.
authors: Department of Chemistry and Biochemistry.
authors: Haneul
authors: H
authors: Yoo
authors: Molecular Biology Interdepartmental PhD Program, University of California, Los Angeles, Los Angeles, CA 90095.
authors: Elizabeth A
authors: EA
authors: Roth-Johnson
authors: Molecular Biology Interdepartmental PhD Program, University of California, Los Angeles, Los Angeles, CA 90095.
authors: Batbileg
authors: B
authors: Bor
authors: Department of Chemistry and Biochemistry Molecular Biology Institute, University of California, Los Angeles, Los Angeles, CA 90095 margot@chem.ucla.edu.
authors: Margot E
authors: ME
authors: Quinlan
mesh_terms: D008841:Actin Cytoskeleton / Q000378:metabolism*; D000483:Alleles; D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D000818:Animals; D029721:Drosophila Proteins / Q000235:genetics* / Q000378:metabolism; D004331:Drosophila melanogaster / Q000378:metabolism*; D005260:Female; D005298:Fertility / Q000235:genetics; D008840:Microfilament Proteins / Q000235:genetics* / Q000378:metabolism; D008969:Molecular Sequence Data; D020125:Mutation, Missense; D009866:Oogenesis / Q000235:genetics / Q000502:physiology*
chemical_list: D029721:Drosophila Proteins; D008840:Microfilament Proteins; C096354:capu protein, Drosophila