title: ADF/cofilin is not essential but is critically important for actin activities during phagocytosis in Tetrahymena thermophila.
abstract: ADF/cofilin is a highly conserved actin-modulating protein. Reorganization of the actin cytoskeleton in vivo through severing and depolymerizing of F-actin by this protein is essential for various cellular events, such as endocytosis, phagocytosis, cytokinesis, and cell migration. We show that in the ciliate Tetrahymena thermophila, the ADF/cofilin homologue Adf73p associates with actin on nascent food vacuoles. Overexpression of Adf73p disrupted the proper localization of actin and inhibited the formation of food vacuoles. In vitro, recombinant Adf73p promoted the depolymerization of filaments made of T. thermophila actin (Act1p). Knockout cells lacking the ADF73 gene are viable but grow extremely slowly and have a severely decreased rate of food vacuole formation. Knockout cells have abnormal aggregates of actin in the cytoplasm. Surprisingly, unlike the case in animals and yeasts, in Tetrahymena, ADF/cofilin is not required for cytokinesis. Thus, the Tetrahymena model shows promise for future studies of the role of ADF/cofilin in vivo.
authors.affiliation: Structural Biosciences, Graduate School of Life and Environmental Sciences, University of Tsukuba, Tsukuba, Ibaraki, Japan.
authors.forename: Nanami
authors.initials: N
authors.lastname: Shiozaki
authors.forename: Kentaro
authors.initials: K
authors.lastname: Nakano
authors.forename: Yasuharu
authors.initials: Y
authors.lastname: Kushida
authors.forename: Taro Q P
authors.initials: TQ
authors.lastname: Noguchi
authors.forename: Taro Q P
authors.initials: TQ
authors.lastname: Uyeda
authors.forename: Dorota
authors.initials: D
authors.lastname: Wloga
authors.forename: Drashti
authors.initials: D
authors.lastname: Dave
authors.forename: Krishna Kumar
authors.initials: KK
authors.lastname: Vasudevan
authors.forename: Jacek
authors.initials: J
authors.lastname: Gaertig
authors.forename: Osamu
authors.initials: O
authors.lastname: Numata
mesh_terms: D008841:Actin Cytoskeleton / Q000378:metabolism; D000199:Actins / Q000378:metabolism*; D016770:Ciliophora Infections / Q000235:genetics / Q000382:microbiology; D051338:Cofilin 1 / Q000235:genetics* / Q000378:metabolism; D048749:Cytokinesis / Q000235:genetics; D055786:Gene Knockout Techniques; D008840:Microfilament Proteins / Q000235:genetics*; D010587:Phagocytosis / Q000235:genetics*; D017386:Sequence Homology, Amino Acid; D016808:Tetrahymena thermophila / Q000254:growth & development* / Q000378:metabolism* / Q000472:pathogenicity; D014617:Vacuoles / Q000378:metabolism
chemical_list: D000199:Actins; D051338:Cofilin 1; D008840:Microfilament Proteins