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The KlSTE2 and KlSTE3 genes encode MATα ‐ and MAT a‐specific G‐protein‐coupled receptors, respectively, which are required for mating of Kluyveromyces lactis haploid cells
Author(s) -
TorresQuiroz Francisco,
Kawasaki Laura,
RodríguezGonzález Miriam,
PatrónSoberano Araceli,
Coria Roberto
Publication year - 2007
Publication title -
yeast
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.923
H-Index - 102
eISSN - 1097-0061
pISSN - 0749-503X
DOI - 10.1002/yea.1432
Subject(s) - biology , kluyveromyces lactis , saccharomyces cerevisiae , mating type , gene , pheromone , mating of yeast , receptor , protein subunit , g protein , microbiology and biotechnology , genetics
Mating in yeast is initiated by binding of pheromone to G‐protein‐coupled receptors expressed in haploid cells. We analysed the role of KlSte2p and KlSte3p receptors in the Kluyveromyces lactis mating pathway. By sequence analysis, KlSte2p and KlSte3p are the homologues of the Saccharomyces cerevisiae α‐pheromone and a‐pheromone receptors, respectively. However, by expression experiments, we determined that KlSTE2 gene is expressed in the cells typified as MAT α and therefore is the receptor for the K. lactis a‐pheromone and KlSTE3 gene is expressed in the MAT a cells and binds the α‐pheromone. The KlSTE2 gene is silent in MAT a cells, while it is highly expressed in MATα cells, and conversely the KlSTE3 gene is expressed in MAT a cells and repressed in MATα cells. Disruption mutants of both genes were found to be sterile, and this defect is reversed by plasmidic copies of each gene. The cytoplasmic C‐terminus of KlSte3p interacts strongly with the KlGpa1p (Gα) subunit, which is involved in the transduction of the pheromone stimulus to induce mating. Remarkably, this same domain does not interact with a constitutive active allele of the Gα subunit, indicating that the C‐terminus is able to discriminate between the active (GTP‐bound) and inactive (GDP‐bound) forms of the Gα subunit. Copyright © 2007 John Wiley & Sons, Ltd.