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Open Access Research

Novel G-protein-coupled receptor-like proteins in the plant pathogenic fungus Magnaporthe grisea

Resham D Kulkarni12, Michael R Thon13, Huaqin Pan1 and Ralph A Dean1*

Author Affiliations

1 Fungal Genomics Laboratory, Center for Integrated Fungal Research, North Carolina State University, Raleigh, NC 27695, USA

2 Current address: Bioinformatics Program, Research Computing Division, RTI International, 3040 Cornwallis Road, Research Triangle Park, NC 27707, USA

3 Program for Biology of Filamentous Fungi, Department of Plant Pathology and Microbiology, Texas A&M University, College Station, TX 77843, USA

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Genome Biology 2005, 6:R24  doi:10.1186/gb-2005-6-3-r24

Published: 2 March 2005

Abstract

Background

The G-protein-coupled receptors (GPCRs) are one of the largest protein families in human and other animal genomes, but no more than 10 GPCRs have been characterized in fungi. Do fungi contain only this handful or are there more receptors to be discovered? We asked this question using the recently sequenced genome of the fungal plant pathogen Magnaporthe grisea.

Results

Proteins with significant similarity to fungus-specific and other eukaryotic GPCRs were identified in M. grisea. These included homologs of known fungal GPCRs, the cAMP receptors from Dictyostelium, and a steroid receptor mPR. We also identified a novel class of receptors typified by PTH11, a cell-surface integral membrane protein required for pathogenicity. PTH11 has seven transmembrane regions and an amino-terminal extracellular cysteine-rich EGF-like domain (CFEM domain), a characteristic also seen in human GPCRs. Sixty-one PTH11-related proteins were identified in M. grisea that shared a common domain with homologs in Neurospora crassa and other fungi belonging to this subphylum of the Ascomycota (the Pezizomycotina). None was detected in other fungal groups (Basidiomycota or other Ascomycota subphyla, including yeasts) or any other eukaryote. The subclass of PTH11 containing the CFEM domain is highly represented in M. grisea.

Conclusion

In M. grisea we identified homologs of known GPCRs and a novel class of GPCR-like receptors specific to filamentous ascomycetes. A member of this new class, PTH11, is required for pathogenesis, thus suggesting roles in pathogenicity for other members. The identified classes constitute the largest number of GPCR-like proteins reported in fungi to date.