Dynacortin, a genetic link between equatorial contractility and global shape control discovered by library complementation of a Dictyostelium discoideum cytokinesis mutant.
We have developed a system for performing interaction genetics in Dictyostelium discoideum that uses a cDNA library complementation/multicopy suppression strategy. Chemically mutagenized cells were screened for cytokinesis-deficient mutants and one mutant was subjected to library complementation. Isolates of four different genes were recovered as modifiers of this strain's cytokinesis defect. These include the cleavage furrow protein cortexillin I, a novel protein we named dynacortin, an ezrin-radixin-moesin-family protein, and coronin. The cortexillin I locus and transcript were found to be disrupted in the strain, identifying it as the affected gene. Dynacortin is localized partly to the cell cortex and becomes enriched in protrusive regions, a localization pattern that is similar to coronin and partly dependent on RacE. During cytokinesis, dynacortin is found in the cortex and is somewhat enriched at the poles. Furthermore, it appears to be reduced in the cleavage furrow. The genetic interactions and the cellular distributions of the proteins suggest a hypothesis for cytokinesis in which the contraction of the medial ring is a function of spatially restricted cortexillin I and myosin II and globally distributed dynacortin, coronin, and RacE.
Robinson
D N
DN
Department of Biochemistry and Developmental Biology, Beckman Center, Stanford University, Stanford, California 94305-5307, USA. drobinso@cmgm.stanford.edu
Spudich
J A
JA
D000595:Amino Acid Sequence; D000818:Animals; D018797:Cell Cycle Proteins / Q000235:genetics / Q000502:physiology*; D002455:Cell Division / Q000235:genetics; D048429:Cell Size; D004023:Dictyostelium / Q000166:cytology* / Q000235:genetics / Q000502:physiology*; D017353:Gene Deletion; D015723:Gene Library; D005816:Genetic Complementation Test; D007700:Kinetics; D008840:Microfilament Proteins / Q000235:genetics / Q000502:physiology; D008969:Molecular Sequence Data; D016296:Mutagenesis; D015800:Protozoan Proteins; D015183:Restriction Mapping; D014158:Transcription, Genetic
D018797:Cell Cycle Proteins; D008840:Microfilament Proteins; D015800:Protozoan Proteins; C101109:ctxA protein, Dictyostelium discoideum; C413645:dct protein, Dictyostelium discoideum