Open AccessThe G-Protein β Subunit GPB1 Is Required for Mating and Haploid Fruiting in Cryptococcus neoformans
Author(s) -
Ping Wang,
John R. Perfect,
Joseph Heitman
Publication year - 2000
Publication title -
molecular and cellular biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.14
H-Index - 327
eISSN - 1067-8824
pISSN - 0270-7306
DOI - 10.1128/mcb.20.1.352-362.2000
Subject(s) - biology , cryptococcus neoformans , protein subunit , virulence , mating , mating type , tor signaling , protein kinase a , mutant , microbiology and biotechnology , mating of yeast , genetics , gene , sex pheromone , kinase
Cryptococcus neoformans is an opportunistic fungal pathogen with a defined sexual cycle. The gene encoding a heterotrimeric G-protein β subunit, GPB1, was cloned and disrupted.gpb1 mutant strains are sterile, indicating a role for this gene in mating. GPB1 plays an active role in mediating responses to pheromones in early mating steps (conjugation tube formation and cell fusion) and signals via a mitogen-activated protein (MAP) kinase cascade in bothMAT α andMAT a cells. The functions of GPB1 are distinct from those of the Gα protein GPA1, which functions in a nutrient-sensing cyclic AMP (cAMP) pathway required for mating, virulence factor induction, and virulence.gpb1 mutant strains are also defective in monokaryotic fruiting in response to nitrogen starvation. We show thatMAT a cells stimulate monokaryotic fruiting ofMAT α cells, possibly in response to mating pheromone, which may serve to disperse cells and spores to locate mating partners. In summary, the Gβ subunit GPB1 and the Gα subunit GPA1 function in distinct signaling pathways: one (GPB1) senses pheromones and regulates mating and haploid fruiting via a MAP kinase cascade, and the other (GPA1) senses nutrients and regulates mating, virulence factors, and pathogenicity via a cAMP cascade.