Characterization of the ERK homologue CpMK2 from the chestnut blight fungus Cryphonectria parasitica.
The Cryphonectria parasitica gene cpmk2, which encodes a mitogen-activated protein kinase belonging to the yeast extracellular signalling-regulated kinase (YERK1) subfamily, was isolated and its biological function was examined. Disruption of cpmk2 resulted in impaired pigmentation and abolished conidiation. Growth defects were observed in the cpmk2 mutant grown on solid plates, but growth of the mutant appeared normal in liquid media, including EP complete and PD broth, suggesting that the cpmk2 gene is involved in sensing and responding to growth conditions. The mutant's production of laccase, as measured by the size of the coloured area produced on tannic-acid-supplemented plates, was significantly reduced compared with the wild-type, but the intensity of the coloured area was unchanged, suggesting that the reduced laccase activity was owing to reduced growth on solid media rather than transcriptional downregulation. A dramatic reduction observed in the canker area produced by the cpmk2 mutant compared with the wild-type, even more severe than that of a hypovirulent strain, can also be ascribed to defective growth on solid surfaces rather than to impairments in a virulence factor(s). Downregulation of the pheromone gene Mf2/1 was also observed in the mutant, indicating a possible explanation for the regulation of the pheromone precursor gene in filamentous fungi and suggesting the presence of the yeast-like pheromone-responsive pathway in C. parasitica. Immunoblot analyses revealed that the phosphorylation level of CpMK2 increased in both virus-free and virus-containing strains in liquid cultures of up to 5 days old and decreased in older cultures. Moreover, the CpMK2 phosphorylation level increased in both strains after transfer from liquid to solid medium. However, levels of phosphorylated CpMK2 were similar in the two strains, suggesting that CpMK2, unlike CpMK1, is not under the direct control of a hypovirus.
Choi
Eun-Sil
ES
Institute for Molecular Biology and Genetics, Basic Science Research Institute, Chonbuk National University, Jeonju, Chonbuk 561-756, Korea.
Chung
Hea-Jong
HJ
Institute for Molecular Biology and Genetics, Basic Science Research Institute, Chonbuk National University, Jeonju, Chonbuk 561-756, Korea.
Kim
Myoung-Ju
MJ
Institute for Molecular Biology and Genetics, Basic Science Research Institute, Chonbuk National University, Jeonju, Chonbuk 561-756, Korea.
Park
Seung-Moon
SM
Institute for Molecular Biology and Genetics, Basic Science Research Institute, Chonbuk National University, Jeonju, Chonbuk 561-756, Korea.
Cha
Byeong-Jin
BJ
Department of Agricultural Biology, Chungbuk National University, Cheongju, Chungbuk 361-763, Korea.
Yang
Moon-Sik
MS
Institute for Molecular Biology and Genetics, Basic Science Research Institute, Chonbuk National University, Jeonju, Chonbuk 561-756, Korea.
Kim
Dae-Hyuk
DH
Institute for Molecular Biology and Genetics, Basic Science Research Institute, Chonbuk National University, Jeonju, Chonbuk 561-756, Korea.
D001203:Ascomycota / Q000201:enzymology* / Q000235:genetics / Q000472:pathogenicity / Q000821:virology; D003470:Culture Media; D004926:Escherichia coli / Q000201:enzymology / Q000235:genetics; D005656:Fungal Proteins / Q000235:genetics / Q000378:metabolism; D017353:Gene Deletion; D015966:Gene Expression Regulation, Fungal; D015151:Immunoblotting; D048052:Mitogen-Activated Protein Kinase 3 / Q000235:genetics; D020928:Mitogen-Activated Protein Kinases / Q000737:chemistry / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism; D008969:Molecular Sequence Data; D010675:Pheromones / Q000235:genetics / Q000378:metabolism; D010766:Phosphorylation; D010935:Plant Diseases / Q000382:microbiology*; D014197:Trees / Q000382:microbiology*; D014774:Virulence
D003470:Culture Media; D005656:Fungal Proteins; D010675:Pheromones; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases