The Ste20-like kinase SvkA of Dictyostelium discoideum is essential for late stages of cytokinesis.
The genome of the social amoeba Dictyostelium discoideum encodes approximately 285 kinases, which represents approximately 2.6% of the total genome and suggests a signaling complexity similar to that of yeasts and humans. The behavior of D. discoideum as an amoeba and during development relies heavily on fast rearrangements of the actin cytoskeleton. Here, we describe the knockout phenotype of the svkA gene encoding severin kinase, a homolog of the human MST3, MST4 and YSK1 kinases. SvkA-knockout cells show drastic defects in cytokinesis, development and directed slug movement. The defect in cytokinesis is most prominent, leading to multinucleated cells sometimes with >30 nuclei. The defect arises from the frequent inability of svkA-knockout cells to maintain symmetry during formation of the cleavage furrow and to sever the last cytosolic connection. We demonstrate that GFP-SvkA is enriched at the centrosome and localizes to the midzone during the final stage of cell division. This distribution is mediated by the C-terminal half of the kinase, whereas a rescue of the phenotypic changes requires the active N-terminal kinase domain as well. The data suggest that SvkA is part of a regulatory pathway from the centrosome to the midzone, thus regulating the completion of cell division.
Adolf-Butenandt-Institut/Zellbiologie, Ludwig-Maximilians-Universität, Schillerstr. 42, 80336 München, Germany.
Meino
M
Rohlfs
Rajesh
R
Arasada
Petros
P
Batsios
Julia
J
Janzen
Michael
M
Schleicher
D000818:Animals; D002455:Cell Division / Q000502:physiology; D016764:Cell Polarity / Q000502:physiology; D018385:Centrosome / Q000378:metabolism; D048749:Cytokinesis / Q000502:physiology*; D004023:Dictyostelium / Q000166:cytology / Q000201:enzymology / Q000235:genetics / Q000502:physiology*; D017125:Genes, Protozoan; D010641:Phenotype; D017346:Protein Serine-Threonine Kinases / Q000235:genetics / Q000378:metabolism*; D015800:Protozoan Proteins / Q000235:genetics / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000378:metabolism
D015800:Protozoan Proteins; D011993:Recombinant Fusion Proteins; C112607:severin kinase, Dictyostelium; D017346:Protein Serine-Threonine Kinases