a p21-activated kinase is required for conidial germination in penicillium marneffei需要短暂快速脉冲刺激导致蛋白激酶21个特异marneffei分生孢子的萌发.pdfVIP

A p21-Activated Kinase Is Required for Conidial Germination in Penicillium marneffei * Kylie J. Boyce, Alex Andrianopoulos Department of Genetics, University of Melbourne, Victoria, Australia Asexual spores (conidia) are the infectious propagules of many pathogenic fungi, and the capacity to sense the host environment and trigger conidial germination is a key pathogenicity determinant. Germination of conidia requires the de novo establishment of a polarised growth axis and consequent germ tube extension. The molecular mechanisms that control polarisation during germination are poorly understood. In the dimorphic human pathogenic fungus Penicillium marneffei, conidia germinate to produce one of two cell types that have very different fates in response to an environmental cue. At 25 8C, conidia germinate to produce the saprophytic cell type, septate, multinucleate hyphae that have the capacity to undergo asexual development. At 37 8C, conidia germinate to produce the pathogenic cell type, arthroconidiating hyphae that liberate uninucleate yeast cells. This study shows that the p21-activated kinase pakA is an essential component of the polarity establishment machinery during conidial germination and polarised growth of yeast cells at 37 8C but is not required for germination or polarised growth at 25 8C. Analysis shows that the heterotrimeric G protein a subunit GasC and the CDC42 orthologue CflA lie upstream of PakA for germination at both temperatures, while the Ras orthologue RasA only functions at 25 8C. These findings suggest that although some proteins that regulate the establishment of polarised growth in budding yeast are conserved in filamentous fungi, the circuitry and downstream effectors are differentially regulated to give rise to distinct cell types. Citation: Boyce KJ, Andrianopoulos A (2007) A p21-activated kinase is required for conidial germination in P