Versatile and ubiquitous, G-protein coupled receptors (GPCRs) are the busybodies of eukaryotic signaling. This diverse group of stimulus-sensing membrane proteins are involved in countless aspects of growth, development, immunity, metabolism, and response to environmental conditions. In the latest issue of G3, Cabrera et al. report phenotypic and gene expression data for more than 80% of predicted GPCR genes in the filamentous fungus Neurospora crassa, shedding light on the function of a large class of GPCRs not previously characterized in this species. Much of the experimental work was carried out by members of an undergraduate research class at the University of California, Riverside (UCR)
N. crassa, a type of bread mold, is an important genetic model for pathogenic fungi and for foundational research on topics like circadian rhythms, genome defense, cell polarity, biochemistry, and development. In the wild, this species grows primarily on plants, most famously on the burnt husks left behind by forest fires.
The Neurospora genome includes 43 predicted GPCRs, only five of which had previously been experimentally investigated. The most abundant type of GPCR in filamentous fungi is the Pth11-related class, including 25 in members in Neurospora, yet none of its members have a characterized function.
The research team examined 36 Neurospora GPCR mutants using a comprehensive range of growth, development, and chemical sensitivity phenotypes. They were able to find phenotypes for 28 of the mutants, including 15 from the Pth11-related class. The researchers compared these results to published gene expression data for all predicted GPCRs, revealing groups of genes with potentially related functions.
The results suggest that many Pth11-related GPCRs may play a role in sensing or utilizing cellulose, an abundant carbohydrate in plant cell walls — a crucial function for an organism that typically grows on dead vegetation.
The research was performed in part by students taking the undergraduate research class “Experimental Microbiology” taught by Katherine Borkovich, professor and Chair of the Department of Plant Pathology and Microbiology at UCR, and teaching assistant and graduate student Ilva Cabrera.
“The positive feedback I have received from teaching the course has been very satisfying to me as an instructor,” says Borkovich. “Being involved in this project-based course exposed a large group of students to scientific research, from performing experiments to writing and submitting a paper for publication. Several of the participants are either in graduate school or submitting applications.”
Ilva E. Cabrera, Itallia V. Pacentine, Andrew Lim, Nayeli Guerrero, Svetlana Krystofova, Liande Li, Alexander V. Michkov, Jacqueline A. Servin, Steven R. Ahrendt, Alexander J. Carrillo,Liza M. Davidson, Andrew H. Barsoum, Jackie Cao, Ronald Castillo,Wan-Ching Chen, Alex Dinkchian, Stephanie Kim, Sho M. Kitada, Taffani H. Lai, Ashley Mach, Cristin Malekyan, Toua R. Moua,Carlos Rojas Torres, Alaina Yamamoto, and Katherine A. Borkovich (2015). Global Analysis of Predicted G Protein−Coupled Receptor Genes in the Filamentous Fungus, Neurospora crassa. G3: Genes| Genomes| Genetics, 5(12), 2729-2743. doi:10.1534/g3.115.020974