TY  - JOUR
A1  - Schweigel, Ulrike
A1  - Batsios, Petros
A1  - Müller-Taubenberger, Annette
A1  - Gräf, Ralph
A1  - Grafe, Marianne
T1  - Dictyostelium spastin is involved in nuclear envelope dynamics during semi-closed mitosis
JF  - Nucleus
N2  - Dictyostelium amoebae perform a semi-closed mitosis, in which the nuclear envelope is fenestrated at the insertion sites of the mitotic centrosomes and around the central spindle during karyokinesis. During late telophase the centrosome relocates to the cytoplasmic side of the nucleus, the central spindle disassembles and the nuclear fenestrae become closed. Our data indicate that Dictyostelium spastin (DdSpastin) is a microtubule-binding and severing type I membrane protein that plays a role in this process. Its mitotic localization is in agreement with a requirement for the removal of microtubules that would hinder closure of the fenestrae. Furthermore, DdSpastin interacts with the HeH/ LEM-family protein Src1 in BioID analyses as well as the inner nuclear membrane protein Sun1, and shows subcellular co-localizations with Src1, Sun1, the ESCRT component CHMP7 and the IST1-like protein filactin, suggesting that the principal pathway of mitotic nuclear envelope remodeling is conserved between animals and Dictyostelium amoebae.
KW  - Spastin
KW  - LEM-domain
KW  - ESCRT
KW  - sun1
KW  - dictyostelium
KW  - nuclear envelope
KW  - mitosis
Y1  - 2022
U6  - https://doi.org/10.1080/19491034.2022.2047289
SN  - 1949-1034
SN  - 1949-1042
VL  - 13
IS  - 1
SP  - 144
EP  - 154
PB  - Taylor & Francis Group
CY  - Philadelphia
ER  - 
TY  - JOUR
A1  - Batsios, Petros
A1  - Ishikawa-Ankerhold, Hellen Christina
A1  - Roth, Heike
A1  - Schleicher, Michael
A1  - Wong, Catherine C. L.
A1  - Müller-Taubenberger, Annette
T1  - Ate1-mediated posttranslational arginylation affects substrate adhesion and cell migration in Dictyostelium discoideum
JF  - Molecular biology of the cell : the official publication of the American Society for Cell Biology
N2  - The highly conserved enzyme arginyl-tRNA-protein transferase (Ate1) mediates arginylation, a posttranslational modification that is only incompletely understood at its molecular level. To investigate whether arginylation affects actin-dependent processes in a simple model organism, Dictyostelium discoideum, we knocked out the gene encoding Ate1 and characterized the phenotype of ate1-null cells. Visualization of actin cytoskeleton dynamics by live-cell microscopy indicated significant changes in comparison to wild-type cells. Ate1-null cells were almost completely lacking focal actin adhesion sites at the substrate-attached surface and were only weakly adhesive. In two-dimensional chemotaxis assays toward folate or cAMP, the motility of ate1-null cells was increased. However, in three-dimensional chemotaxis involving more confined conditions, the motility of ate1-null cells was significantly reduced. Live-cell imaging showed that GFP-tagged Ate1 rapidly relocates to sites of newly formed actin-rich protrusions. By mass spectrometric analysis, we identified four arginylation sites in the most abundant actin isoform of Dictyostelium, in addition to arginylation sites in other actin isoforms and several actin-binding proteins. In vitro polymerization assays with actin purified from ate1-null cells revealed a diminished polymerization capacity in comparison to wild-type actin. Our data indicate that arginylation plays a crucial role in the regulation of cytoskeletal activities.
Y1  - 2019
U6  - https://doi.org/10.1091/mbc.E18-02-0132
SN  - 1059-1524
SN  - 1939-4586
VL  - 30
IS  - 4
SP  - 453
EP  - 466
PB  - American Society for Cell Biology
CY  - Bethesda
ER  -