Global Survey of Canonical Aspergillus flavus G Protein-Coupled Receptors

ABSTRACTG protein-coupled receptors (GPCRs) are transmembrane receptors that relay signals from the external environment inside the cell, allowing an organism to adapt to its surroundings. They are known to detect a vast array of ligands, including sugars, amino acids, pheromone peptides, nitrogen sources, oxylipins, and light. Despite their prevalence in fungal genomes, very little is known about the functions of filamentous fungal GPCRs. Here we present the first full-genome assessment of fungal GPCRs through characterization of null mutants of all 15 GPCRs encoded by the aflatoxin-producing fungusAspergillus flavus. All strains were assessed for growth, development, ability to produce aflatoxin, and response to carbon sources, nitrogen sources, stress agents, and lipids. Most GPCR mutants were aberrant in one or more response processes, possibly indicative of cross talk in downstream signaling pathways. Interestingly, the biological defects of the mutants did not correspond with assignment to established GPCR classes; this is likely due to the paucity of data for characterized fungal GPCRs. Many of the GPCR transcripts were differentially regulated under various conditions as well. The data presented here provide an extensive overview of the full set of GPCRs encoded byA. flavusand provide a framework for analysis in other fungal species.IMPORTANCEAspergillus flavusis an opportunistic pathogen of crops and animals, including humans, and it produces a carcinogenic toxin called aflatoxin. Because of this,A. flavusaccounts for food shortages and economic losses in addition to sickness and death. Effective means of combating this pathogen are needed to mitigate its deleterious effects. G protein-coupled receptors (GPCRs) are often used as therapeutic targets due to their signal specificity, and it is estimated that half of all drugs target GPCRs. In fungi such asA. flavus, GPCRs are likely necessary for sensing the changes in the environment, including food sources, developmental signals, stress agents, and signals from other organisms. Therefore, elucidating their functions inA. flavuscould identify ideal receptors against which to develop antagonists.

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Aspergillus fumigatus G-Protein Coupled Receptors GprM and GprJ Are Important for the Regulation of the Cell Wall Integrity Pathway, Secondary Metabolite Production, and Virulence

mBio ◽

10.1128/mbio.02458-20 ◽

2020 ◽

Vol 11 (5) ◽

Cited By ~ 1

Author(s):

Aílton Pereira da Costa Filho ◽

Guilherme Thomaz Pereira Brancini ◽

Patrícia Alves de Castro ◽

Clara Valero ◽

Jaire Alves Ferreira Filho ◽

...

Keyword(s):

Cell Wall ◽

G Protein ◽

Galleria Mellonella ◽

G Protein Coupled Receptors ◽

Cell Wall Integrity ◽

Fungal Development ◽

Content Type ◽

Cell Wall Integrity Pathway ◽

Mycotoxin Biosynthesis ◽

G Protein Coupled

ABSTRACT G-protein coupled receptors (GPCRs) are extracellular signaling receptors that sense environmental cues. Fungi sense their environment primarily through GPCR-mediated signaling pathways, which, in turn, regulate fungal development, metabolism, virulence, and mycotoxin biosynthesis. Aspergillus fumigatus is an important human pathogen that causes aspergillosis, a heterogeneous group of diseases that present a wide range of clinical manifestations. Here, we investigate in detail the role of the GPCRs GprM and GprJ in growth and gene expression. GprM and GprJ are important for melanin production and the regulation of the cell wall integrity (CWI) pathway. Overexpression of gprM and gprJ causes a 20 and 50% reduction in growth rate compared to the wild-type (WT) strain and increases sensitivity to cell wall-damaging agents. Phosphorylation of the CWI protein kinase MpkA is increased in the ΔgprM and ΔgprJ strains and decreased in the overexpression mutants compared to the WT strain. Furthermore, differences in cell wall polysaccharide concentrations and organization were observed in these strains. Transcriptome sequencing suggests that GprM and GprJ negatively regulate genes encoding secondary metabolites (SMs). Mass spectrometry analysis confirmed that the production of fumagillin, pyripyropene, fumigaclavine C, fumiquinazoline, and fumitremorgin is reduced in the ΔgprM and ΔgprJ strains, at least partially through the activation of MpkA. Overexpression of grpM also resulted in the regulation of many transcription factors, with AsgA predicted to function downstream of GprM and MpkA signaling. Finally, we show that the ΔgprM and ΔgprJ mutants are reduced in virulence in the Galleria mellonella insect model of invasive aspergillosis. IMPORTANCE A. fumigatus is the main etiological agent of invasive pulmonary aspergillosis, a life-threatening fungal disease that occurs in severely immunocompromised humans. Withstanding the host environment is essential for A. fumigatus virulence, and sensing of extracellular cues occurs primarily through G-protein coupled receptors (GPCRs) that activate signal transduction pathways, which, in turn, regulate fungal development, metabolism, virulence, and mycotoxin biosynthesis. The A. fumigatus genome encodes 15 putative classical GPCRs, with only three having been functionally characterized to date. In this work, we show that the two GPCRs GprM and GprJ regulate the phosphorylation of the mitogen-activated protein kinase MpkA and thus control the regulation of the cell wall integrity pathway. GprM and GprJ are also involved in the regulation of the production of the secondary metabolites fumagillin, pyripyropene, fumigaclavine C, fumiquinazoline, melanin, and fumitremorgin, and this regulation partially occurs through the activation of MpkA. Furthermore, GprM and GprJ are important for virulence in the insect model Galleria mellonella. This work therefore functionally characterizes two GPCRs and shows how they regulate several intracellular pathways that have been shown to be crucial for A. fumigatus virulence.

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Identification of a Conserved, Orphan G Protein-Coupled Receptor Required for Efficient Pathogen Clearance in Caenorhabditis elegans

Infection and Immunity ◽

10.1128/iai.00034-19 ◽

2019 ◽

Vol 87 (4) ◽

Cited By ~ 2

Author(s):

Alexandra Anderson ◽

Yee Lian Chew ◽

William Schafer ◽

Rachel McMullan

Keyword(s):

Caenorhabditis Elegans ◽

Immune Responses ◽

G Protein ◽

G Protein Coupled Receptors ◽

G Protein Coupled Receptor ◽

Content Type ◽

C Elegans ◽

Host Immune Responses ◽

Pathogen Clearance ◽

G Protein Coupled

ABSTRACT G protein-coupled receptors contribute to host defense across the animal kingdom, transducing many signals involved in both vertebrate and invertebrate immune responses. While it has become well established that the nematode worm Caenorhabditis elegans triggers innate immune responses following infection with numerous bacterial, fungal, and viral pathogens, the mechanisms by which C. elegans recognizes these pathogens have remained somewhat more elusive. C. elegans G protein-coupled receptors have been implicated in recognizing pathogen-associated damage and activating downstream host immune responses. Here we identify and characterize a novel G protein-coupled receptor required to regulate the C. elegans response to infection with Microbacterium nematophilum. We show that this receptor, which we designate pathogen clearance-defective receptor 1 (PCDR-1), is required for efficient pathogen clearance following infection. PCDR-1 acts upstream of multiple G proteins, including the C. elegans Gαq ortholog, EGL-30, in rectal epithelial cells to promote pathogen clearance via a novel mechanism.

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GPR11, a Putative Seven-Transmembrane G Protein-Coupled Receptor, Controls Zoospore Development and Virulence of Phytophthora sojae

Eukaryotic Cell ◽

10.1128/ec.00265-09 ◽

2009 ◽

Vol 9 (2) ◽

pp. 242-250 ◽

Cited By ~ 19

Author(s):

Yonglin Wang ◽

Aining Li ◽

Xiaoli Wang ◽

Xin Zhang ◽

Wei Zhao ◽

...

Keyword(s):

G Protein ◽

Hyphal Growth ◽

Phytophthora Sojae ◽

G Protein Coupled Receptors ◽

Yeast Two Hybrid ◽

Content Type ◽

Signaling Mechanisms ◽

G Protein Coupled ◽

Two Hybrid ◽

Receptor Family

ABSTRACT G protein-coupled receptors (GPCRs) represent a large receptor family involved in a broad spectrum of cell signaling. To understand signaling mechanisms mediated by GPCRs in Phytophthora sojae, we identified and characterized the PsGPR11 gene, which encodes a putative seven-transmembrane GPCR. An expression analysis revealed that PsGPR11 was differentially expressed during asexual development. The highest expression level occurred in zoospores and was upregulated during early infection. PsGPR11-deficienct transformants were obtained by gene silencing strategies. Silenced transformants exhibited no differences in hyphal growth or morphology, sporangium production or size, or mating behavior. However, the release of zoospores from sporangia was severely impaired in the silenced transformants, and about 50% of the sporangia did not completely release their zoospores. Zoospore encystment and germination were also impaired, and zoospores of the transformants lost their pathogenicity to soybean. In addition, no interaction was observed between PsGPR11 and PsGPA1 with a conventional yeast two-hybrid assay, and the transcriptional levels of some genes which were identified as being negatively regulated by PsGPA1 were not clearly altered in PsGPR11-silenced mutants. These results suggest that PsGPR11-mediated signaling controls P. sojae zoospore development and virulence through the pathways independent of G protein.

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Identification and Expression Analysis of G Protein-Coupled Receptors in the Miridae Insect Apolygus lucorum

Frontiers in Endocrinology ◽

10.3389/fendo.2021.773669 ◽

2021 ◽

Vol 12 ◽

Author(s):

Han Gao ◽

Yanxiao Li ◽

Miao Wang ◽

Xiaowen Song ◽

Jing Tang ◽

...

Keyword(s):

G Protein ◽

Developmental Stages ◽

Expression Profiles ◽

Vital Role ◽

G Protein Coupled Receptors ◽

Economic Losses ◽

Apolygus Lucorum ◽

Physiological Processes ◽

And Control ◽

G Protein Coupled

G protein-coupled receptors (GPCRs) are the largest and most versatile family of transmembrane receptors in the cell and they play a vital role in the regulation of multiple physiological processes. The family Miridae (Hemiptera: Heteroptera) is one of the most diverse families of insects. Until now, information on GPCRs has been lacking in Miridae. Apolygus lucorum, a representative species of the Miridae, is an omnivorous pest that occurs worldwide and is notorious for causing serious damage to various crops and substantial economic losses. By searching the genome, 133 GPCRs were identified in A. lucorum. Compared with other model insects, we have observed GPCR genes to be remarkably expanded in A. lucorum, especially focusing on biogenic amine receptors and neuropeptide receptors. Among these, there is a novel large clade duplicated from known FMRFamide receptors (FMRFaRs). Moreover, the temporal and spatial expression profiles of the 133 genes across developmental stages were determined by transcriptome analysis. Most GPCR genes showed a low expression level in the whole organism of A. lucorum. However, there were a few highly expressed GPCR genes. The highly expressed LW opsins in the head probably relate to nocturning of A. lucorum, and the expression of Cirl at different times and in different tissues indicated it may be involved in growth and development of A. lucorum. We also found C2 leucine-rich repeat-containing GPCRs (LGRs) were mainly distributed in Hemiptera and Phthiraptera among insects. Our study was the first investigation on GPCRs in A. lucorum and it provided a molecular target for the regulation and control of Miridae pests.

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