Self-Compatible B Mutants in Coprinus With Altered Pheromone-Receptor Specificities

Corresponding author: Lorna A. Casselton, Department of Plant Sciences, University of Oxford, Oxford OX1 3RB, United Kingdom., lorna.casselton{at}plants.ox.ac.uk (E-mail)

Communicating editor: R. H. DAVIS

A successful mating in the mushroom Coprinus cinereus brings together a compatible complement of pheromones and G-protein-coupled receptors encoded by multiallelic genes at the B mating-type locus. Rare B gene mutations lead to constitutive activation of B-regulated development without the need for mating. Here we characterize a mutation that arose in the B6 locus and show that it generates a mutant receptor with a single amino acid substitution (R96H) at the intracellular end of transmembrane domain III. Using a heterologous yeast assay and synthetic pheromones we show that the mutation does not make the receptor constitutively active but permits it to respond inappropriately to a normally incompatible pheromone encoded within the same B6 locus. Parallel experiments carried out in Coprinus showed that a F67W substitution in this same pheromone enabled it to activate the normally incompatible wild-type receptor. Together, our experiments show that a single amino acid replacement in either pheromone or receptor can deregulate the specificity of ligand-receptor recognition and confer a self-compatible B phenotype. In addition, we use the yeast assay to demonstrate that different receptors and pheromones found at a single B locus belong to discrete subfamilies within which receptor activation cannot normally occur.

This article has been cited by other articles:

				T. Y. James, P. Srivilai, U. Kues, and R. Vilgalys Evolution of the Bipolar Mating System of the Mushroom Coprinellus disseminatus From Its Tetrapolar Ancestors Involves Loss of Mating-Type-Specific Pheromone Receptor Function Genetics, March 1, 2006; 172(3): 1877 - 1891. [Abstract] [Full Text] [PDF]

				M. Riquelme, M. P. Challen, L. A. Casselton, and A. J. Brown The Origin of Multiple B Mating Specificities in Coprinus cinereus Genetics, July 1, 2005; 170(3): 1105 - 1119. [Abstract] [Full Text] [PDF]

				A. J. Brown, S. M. Goldsworthy, A. A. Barnes, M. M. Eilert, L. Tcheang, D. Daniels, A. I. Muir, M. J. Wigglesworth, I. Kinghorn, N. J. Fraser, et al. The Orphan G Protein-coupled Receptors GPR41 and GPR43 Are Activated by Propionate and Other Short Chain Carboxylic Acids J. Biol. Chem., March 21, 2003; 278(13): 11312 - 11319. [Abstract] [Full Text] [PDF]

				W.-C. Shen, R. C. Davidson, G. M. Cox, and J. Heitman Pheromones Stimulate Mating and Differentiation via Paracrine and Autocrine Signaling in Cryptococcus neoformans Eukaryot. Cell, June 1, 2002; 1(3): 366 - 377. [Abstract] [Full Text] [PDF]

				T. J. Fowler, M. F. Mitton, L. J. Vaillancourt, and C. A. Raper Changes in Mate Recognition Through Alterations of Pheromones and Receptors in the Multisexual Mushroom Fungus Schizophyllum commune Genetics, August 1, 2001; 158(4): 1491 - 1503. [Abstract] [Full Text] [PDF]