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Eukaryot Cell

Title:		Barrier activity in Candida albicans mediates pheromone degradation and promotes mating
Author(s):		Schaefer D; Cote P; Whiteway M; Bennett RJ;
Address:		"MMI Department, Brown University, 171 Meeting Street, Providence, RI 02912, USA"
Journal Title:		Eukaryot Cell
Year:		2007
Volume:		20070406
Issue:		6
Page Number:		907 - 918
DOI:		10.1128/EC.00090-07
ISSN/ISBN:		1535-9778 (Print) 1535-9786 (Electronic) 1535-9786 (Linking)
Abstract:		"Mating in Candida albicans and Saccharomyces cerevisiae is regulated by the secretion of peptide pheromones that initiate the mating process. An important regulator of pheromone activity in S. cerevisiae is barrier activity, involving an extracellular aspartyl protease encoded by the BAR1 gene that degrades the alpha pheromone. We have characterized an equivalent barrier activity in C. albicans and demonstrate that the loss of C. albicans BAR1 activity results in opaque a cells exhibiting hypersensitivity to alpha pheromone. Hypersensitivity to pheromone is clearly seen in halo assays; in response to alpha pheromone, a lawn of C. albicans Deltabar1 mutant cells produces a marked zone in which cell growth is inhibited, whereas wild-type strains fail to show halo formation. C. albicans mutants lacking BAR1 also exhibit a striking mating defect in a cells, but not in alpha cells, due to overstimulation of the response to alpha pheromone. The block to mating occurs prior to cell fusion, as very few mating zygotes were observed in mixes of Deltabar1 a and alpha cells. Finally, in a barrier assay using a highly pheromone-sensitive strain, we were able to demonstrate that barrier activity in C. albicans is dependent on Bar1p. These studies reveal that a barrier activity to alpha pheromone exists in C. albicans and that the activity is analogous to that caused by Bar1p in S. cerevisiae"
Keywords:		"Aspartic Acid Endopeptidases/genetics/metabolism Base Sequence Candida albicans/cytology/genetics/*physiology Cell Shape Gene Deletion *Genes, Mating Type, Fungal Humans Mating Factor Molecular Sequence Data Mutation Peptides/*metabolism Pheromones/*metab;"
Notes:		"MedlineSchaefer, Dana Cote, Pierre Whiteway, Malcolm Bennett, Richard J eng Research Support, Non-U.S. Gov't 2007/04/10 Eukaryot Cell. 2007 Jun; 6(6):907-18. doi: 10.1128/EC.00090-07. Epub 2007 Apr 6"