A role for the DNA-damage checkpoint kinase Chk1 in the virulence program of the fungus Ustilago maydis.
During induction of the virulence program in the phytopathogenic fungus Ustilago maydis, the cell cycle is arrested on the plant surface and it is not resumed until the fungus enters the plant. The mechanism of this cell cycle arrest is unknown, but it is thought that it is necessary for the correct implementation of the virulence program. Here, we show that this arrest takes place in the G2 phase, as a result of an increase in the inhibitory phosphorylation of the catalytic subunit of the mitotic cyclin-dependent kinase Cdk1. Sequestration in the cytoplasm of the Cdc25 phosphatase seems to be one of the reasons for the increase in inhibitory phosphorylation. Strikingly, we also report the DNA-damage checkpoint kinase Chk1 appears to be involved in this process. Our results support the emerging idea that checkpoint kinases have roles other than in the DNA-damage response, by virtue of their ability to interact with the cell cycle machinery.
Departamento de Biotecnología Microbiana, Centro Nacional de Biotecnología CSIC, Campus de Cantoblanco-UAM, 28049 Madrid, Spain.
Natalia
N
Mielnichuk
Cecilia
C
Sgarlata
José
J
Pérez-Martín
D016203:CDC2 Protein Kinase / Q000235:genetics / Q000378:metabolism*; D020134:Catalytic Domain / Q000502:physiology; D000071877:Checkpoint Kinase 1; D016213:Cyclins / Q000378:metabolism; D003593:Cytoplasm / Q000378:metabolism; D015536:Down-Regulation / Q000502:physiology; D005656:Fungal Proteins / Q000235:genetics / Q000378:metabolism; D016195:G2 Phase / Q000502:physiology*; D005818:Genetic Engineering; D010766:Phosphorylation / Q000502:physiology; D011494:Protein Kinases / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction / Q000502:physiology; D014588:Ustilago / Q000166:cytology / Q000378:metabolism* / Q000472:pathogenicity; D020687:cdc25 Phosphatases / Q000235:genetics / Q000378:metabolism*
D016213:Cyclins; D005656:Fungal Proteins; D011494:Protein Kinases; D000071877:Checkpoint Kinase 1; D016203:CDC2 Protein Kinase; D020687:cdc25 Phosphatases