Eight RGS and RGS-like Proteins Orchestrate Growth, Differentiation, and Pathogenicity of Magnaporthe oryzae

Abstract

A previous study identified MoRgs1 as an RGS protein that negative regulates G-protein signaling to control developmental processes such as conidiation and appressorium formation in Magnaporthe oryzae. Here, we characterized additional seven RGS and RGS-like proteins (MoRgs2 through MoRgs8). We found that MoRgs1 and MoRgs4 positively regulate surface hydrophobicity, conidiation, and mating. Indifference to MoRgs1, MoRgs4 has a role in regulating laccase and peroxidase activities. MoRgs1, MoRgs2, MoRgs3, MoRgs4, MoRgs6, and MoRgs7 are important for germ tube growth and appressorium formation. Interestingly, MoRgs7 and MoRgs8 exhibit a unique domain structure in which the RGS domain is linked to a seven-transmembrane motif, a hallmark of G-protein coupled receptors (GPCRs). We have also shown that MoRgs1 regulates mating through negative regulation of Gα MoMagB and is involved in the maintenance of cell wall integrity. While all proteins appear to be involved in the control of intracellular cAMP levels, only MoRgs1, MoRgs3, MoRgs4, and MoRgs7 are required for full virulence. Taking together, in addition to MoRgs1 functions as a prominent RGS protein in M. oryzae, MoRgs4 and other RGS and RGS-like proteins are also involved in a complex process governing asexual/sexual development, appressorium formation, and pathogenicity.

The Genomes of Three Uneven Siblings: Footprints of the Lifestyles of Three Trichoderma Species

“…Whereas RgsB (TR_78314, TA_152907, and 181927) and RgsC (TR_65607, TA_154987, and TV_212406) are still uncharacterized, FlbA (TR_54395, TA_192509, and TV_72112) was shown to promote asexual sporulation through negative regulation of the FadA G␣ protein, and RgsA (TR_72259, TA_41236, and TV_83004) regulates colony growth, aerial hypha formation, and pigmentation by negatively impacting GanB (632,633). Eight RGS and RGS-like proteins have been identified in the plant pathogen M. oryzae that regulate growth, differentiation, and pathogenicity (634). For two of those M. oryzae proteins (MoRgs7 and MoRgs8), the RGS domain is linked to a 7-TM motif, and they represent class VI GPCRs.…”

Functional analyses of regulators of G protein signaling in Gibberella zeae

“…In addition to directly suppressing G protein signaling through GTPase-accelerating protein (GAP) activity, RGS proteins can also enhance the activation of G-protein pathways by acting as effectors, effector antagonists, and scaffolding proteins for receptors, G proteins, or other regulatory molecules (Ballon et al, 2006;Chen and Hamm, 2006;Zhong and Neubig, 2001). Subsequent studies of amino acid substitutions in Ga subunits and disruption of RGS genes have provided additional insight into the mechanisms of G protein signaling and novel functions of RGS proteins in fungi (Hicks et al, 1997;Miyajima et al, 1989;Yu et al, 1996;Zhang et al, 2011). For example, in Saccharomyces cerevisiae, Sst2p has been found to negatively regulate pheromone signaling via inhibition of the Ga subunit (Dietzel and Kurjan, 1987), while other S. cerevisiae RGS proteins, including Rgs2p, Rax1p, and Mdm1p, have been found to be required for stress responses, budding polarity, and mating efficiency (Ballon et al, 2006;Chasse et al, 2006).…”

The Accordant Trend of Both Parameters (rgs Expression and cAMP Content) Follows the Pattern of Development of Fruiting Body in Volvariella volvacea

“…Subsequently, several other RGS proteins were identified in other fungi. RGS and RGS-like proteins play an important role in developmental processes, for instance, cAMP signaling, appressorium formation, mating, and conidiation [19,26,28].…”