Regulation of septum formation in Aspergillus nidulans by a DNA damage checkpoint pathway.
In Aspergillus nidulans, germinating conidia undergo multiple rounds of nuclear division before the formation of the first septum. Previous characterization of temperature-sensitive sepB and sepJ mutations showed that although they block septation, they also cause moderate defects in chromosomal DNA metabolism. Results presented here demonstrate that a variety of other perturbations of chromosomal DNA metabolism also delay septum formation, suggesting that this is a general cellular response to the presence of sublethal DNA damage. Genetic evidence is provided that suggests that high levels of cyclin-dependent kinase (cdk) activity are required for septation in A. nidulans. Consistent with this notion, the inhibition of septum formation triggered by defects in chromosomal DNA metabolism depends upon Tyr-15 phosphorylation of the mitotic cdk p34nimX. Moreover, this response also requires elements of the DNA damage checkpoint pathway. A model is proposed that suggests that the DNA damage checkpoint response represents one of multiple sensory inputs that modulates p34nimX activity to control the timing of septum formation.
Harris
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SD
Department of Microbiology, University of Connecticut Health Center, Farmington 06030-3205, USA. sharris@nso2.uchc.edu
Kraus
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PR
D001233:Aspergillus nidulans / Q000235:genetics* / Q000502:physiology*; D002455:Cell Division / Q000502:physiology; D015825:Chromosomes, Fungal; D018844:Cyclin-Dependent Kinases / Q000378:metabolism; D004249:DNA Damage; D004260:DNA Repair; D004271:DNA, Fungal / Q000378:metabolism; D010766:Phosphorylation; D015398:Signal Transduction; D013997:Time Factors; D014443:Tyrosine / Q000378:metabolism
D004271:DNA, Fungal; D014443:Tyrosine; D018844:Cyclin-Dependent Kinases