Comparative proteomic analyses reveal that the regulators of G-protein signaling proteins regulate amino acid metabolism of the rice blast fungusMagnaporthe oryzae

Abstract

The rice blast fungus Magnaporthe oryzae encodes eight regulators of G-protein (GTP-binding protein) signaling (RGS) proteins MoRgs1-MoRgs8 that orchestrate the growth, asexual/sexual production, appressorium differentiation, and pathogenicity. To address the mechanisms by which MoRgs proteins function, we conducted a 2DE proteome study and identified 82 differentially expressed proteins by comparing five ∆Morgs mutants with wild-type Guy11 strain. We found that the abundances of eight amino acid (AA) biosynthesis or degradation associated proteins were markedly altered in five ∆Morgs mutants, indicating one of the main collective roles for the MoRgs proteins is to influence AA metabolism. We showed that MoRgs proteins have distinct roles in AA metabolism and nutrient responses from growth assays. In addition, we characterized MoLys20 (Lys is lysine), a homocitrate synthase, whose abundance was significantly decreased in the ∆Morgs mutants. The ∆Molys20 mutant is auxotrophic for lys and exogenous lys could partially rescue its auxotrophic defects. Deletion of MoLYS20 resulted in defects in conidiation and infection, as well as pathogenicity on rice. Overall, our results indicate that one of the critical roles for MoRgs proteins is to regulate AA metabolism, and that MoLys20 may be directly or indirectly regulated by MoRgs and participated in lys biosynthesis, thereby affecting fungal development and pathogenicity.

Comparative proteomics of osmotic signal transduction mutants inBotrytis cinereaexplain loss of pathogenicity phenotypes and highlight interaction with cAMP and Ca2+signalling pathways

“…These results highlight the strong impact of protein kinase inactivation on protein production and turnover even in the absence of external stress. This is in agreement with other proteomic studies of fungal ST mutants (Zhang, H et al, 2014;Isasa et al, 2015;Liu et al, 2018;Müller et al, 2018) and, in the case of ∆sak1, with the transcriptional results obtained by Heller and colleagues .…”

“…Only few comparative proteomic studies of intracellular proteins of fungal ST mutants have been published so far (Zhang, H et al, 2014;Isasa et al, 2015;Liu et al, 2018), although their potential to reveal regulations of unsuspected biological functions cannot be denied; e.g., the regulators of G-protein signalling proteins in Magnaporthe oryzae were shown to collectively regulate amino-acid metabolism (Zhang, H et al, 2014), or, in the yeast S. cerevisiae, multiplex comparative proteomics highlighted implication of deubiquitylating proteins in mitochondrial regulation and phosphate metabolism (Isasa et al, 2015).…”

Carbamoyl Phosphate Synthetase Subunit MoCpa2 Affects Development and Pathogenicity by Modulating Arginine Biosynthesis in Magnaporthe oryzae

“…Orotate phosphoribosyl transferase (MoPyr5) is involved in uridine 5′-phosphate synthesis and controls the virulence of M. oryzae (Qi et al, 2016). An aminoadipate reductase (MoLys2) and a homocitrate synthase (MoLys20), regulated by G protein signaling regulators (Rgs), affect lysine biosynthesis and are important for the development and virulence of M. oryzae (Chen et al, 2014; Zhang et al, 2014). Acetolactate synthases (MoIlv2 and MoIlv6) are involved in leucine, isoleucine, and valine biosynthesis, and threonine deaminase (MoIlv1) is involved in isoleucine biosynthesis.…”

Three regulators of G protein signaling differentially affect mating, morphology and virulence in the smut fungus Ustilago maydis

“…This specific effect on late development was surprising as in other fungal pathogens such as M. oryzae , G. zeae , C. neoformans , Fusarium verticillioides , C. parasitica and Candida albicans , the closest orthologs to rgs1 of U. maydis have been demonstrated to be crucial for almost all infection‐related stages such as appressorium formation, host penetration, disease development, surface hydrophobicity, mycotoxin production, conidiation and spore development (Segers et al ., ; Wang et al ., ; Dignard and Whiteway, ; Mukherjee et al ., ; Zhang et al ., ; Park et al ., ). In C. neoformans and C. parasitica the effects on all of these processes were explained through modulation of the cAMP pathway (Segers et al ., ; Mukherjee et al ., ) while in M. oryzae MoRgs1 affects cAMP signaling as well as amino acid metabolism (Liu et al ., ; Zhang et al ., ). In U. maydis rgs1 mutant, we did not observe any alteration in the intracellular cAMP levels (Table ) and we therefore speculate that the sporulation defect is not related to a cAMP‐dependent G protein signaling function, but involves functions connected to the DEP domains of the protein.…”