Characterization of HOG1 homologue, CpMK1, from Cryphonectria parasitica and evidence for hypovirus-mediated perturbation of its phosphorylation in response to hypertonic stress.
We examined the biological function of cpmk1, which encodes a MAPK of Cryphonectria parasitica, and its regulation by mycovirus. Sequence comparisons revealed that cpmk1 had highest homology with osm1, a hog1-homologue from Magnaporthe grisea. A growth defect was observed in the cpmk1-null mutant under hyperosmotic conditions, indicating that cpmk1 functionally belongs to a hog1 subfamily. Immunoblot analyses indicated that the CpMK1 pathway was affected specifically in hyperosmotic conditions by the hypovirus CHV1-EP713. Moreover, the virus-infected hypovirulent UEP1 strain also exhibited severe osmosensitivity compared to the virus-free isogenic strain EP155/2, thus providing additional evidence for viral regulation of cpmk1 in response to a hypertonic stress. Besides osmosensitivity, disruption of cpmk1 resulted in several, but not all, hypovirulence-associated changes, such as reduced pigmentation, conidiation, laccase production and cryparin expression. However, the cpmk1-null mutant exhibited an increased accumulation of pheromone gene transcripts. Virulence assays of the cpmk1-null mutant revealed reduced canker area, but not as severe as that of UEP1. These results suggest that mycoviruses modulate the MAPK and thereby provoke the aberrant expression of target genes, some of which are likely to be implicated in viral symptom development.
Park
Seung-Moon
SM
Institute for Molecular Biology and Genetics, Basic Science Research Institute, Chonbuk National University, Dukjindong 664-14, Jeonju, Chonbuk 561-756, Korea.
Choi
Eun-Sil
ES
Kim
Myoung-Ju
MJ
Cha
Byeong-Jin
BJ
Yang
Moon-Sik
MS
Kim
Dae-Hyuk
DH
D000595:Amino Acid Sequence; D001203:Ascomycota / Q000235:genetics / Q000378:metabolism* / Q000821:virology*; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism; D005656:Fungal Proteins / Q000145:classification / Q000235:genetics / Q000378:metabolism*; D015966:Gene Expression Regulation, Fungal; D005800:Genes, Fungal; D006982:Hypertonic Solutions; D020928:Mitogen-Activated Protein Kinases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D010641:Phenotype; D010766:Phosphorylation; D010802:Phylogeny; D012328:RNA Viruses / Q000502:physiology*; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism; D016415:Sequence Alignment; D015398:Signal Transduction / Q000502:physiology; D014774:Virulence / Q000502:physiology
D005656:Fungal Proteins; D006982:Hypertonic Solutions; D029701:Saccharomyces cerevisiae Proteins; C088589:HOG1 protein, S cerevisiae; D020928:Mitogen-Activated Protein Kinases