A kinesin mutant with an atypical bipolar spindle undergoes normal mitosis.
Motor proteins have been implicated in various aspects of mitosis, including spindle assembly and chromosome segregation. Here, we show that acentrosomal Arabidopsis cells that are mutant for the kinesin, ATK1, lack microtubule accumulation at the predicted spindle poles during prophase and have reduced spindle bipolarity during prometaphase. Nonetheless, all abnormalities are rectified by anaphase and chromosome segregation appears normal. We conclude that ATK1 is required for normal microtubule accumulation at the spindle poles during prophase and possibly functions in spindle assembly during prometaphase. Because aberrant spindle morphology in these mutants is resolved by anaphase, we postulate that mitotic plant cells contain an error-correcting mechanism. Moreover, ATK1 function seems to be dosage-dependent, because cells containing one wild-type allele take significantly longer to proceed to anaphase as compared with cells containing two wild-type alleles.
Marcus
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The Pennsylvania State University, Department of Biology, 208 Mueller Laboratory, University Park, Pennsylvania 16801, USA.
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D000483:Alleles; D000705:Anaphase / Q000502:physiology; D017360:Arabidopsis / Q000166:cytology / Q000235:genetics / Q000502:physiology; D029681:Arabidopsis Proteins / Q000235:genetics* / Q000502:physiology*; D018744:DNA, Plant / Q000235:genetics; D017343:Genes, Plant; D005838:Genotype; D018398:Homeodomain Proteins / Q000737:chemistry / Q000235:genetics / Q000502:physiology; D016547:Kinesins / Q000737:chemistry / Q000235:genetics* / Q000502:physiology*; D008677:Metaphase / Q000502:physiology; D008938:Mitosis / Q000502:physiology*; D020409:Molecular Motor Proteins / Q000737:chemistry / Q000235:genetics / Q000502:physiology; D009154:Mutation; D010641:Phenotype; D018517:Plant Roots / Q000166:cytology / Q000502:physiology; D008941:Spindle Apparatus / Q000502:physiology; D015534:Trans-Activators / Q000737:chemistry / Q000235:genetics / Q000502:physiology
C095214:ATK1 protein, Arabidopsis; D029681:Arabidopsis Proteins; D018744:DNA, Plant; D018398:Homeodomain Proteins; D020409:Molecular Motor Proteins; D015534:Trans-Activators; D016547:Kinesins