The heterotrimeric G-protein GanB(alpha)-SfaD(beta)-GpgA(gamma) is a carbon source sensor involved in early cAMP-dependent germination in Aspergillus nidulans.
The role of heterotrimeric G-proteins in cAMP-dependent germination of conidia was investigated in the filamentous ascomycete Aspergillus nidulans. We demonstrate that the G alpha-subunit GanB mediates a rapid and transient activation of cAMP synthesis in response to glucose during the early period of germination. Moreover, deletion of individual G-protein subunits resulted in defective trehalose mobilization and altered germination kinetics, indicating that GanB(alpha)-SfaD(beta)-GpgA(gamma) constitutes a functional heterotrimer and controls cAMP/PKA signaling in response to glucose as well as conidial germination. Further genetic analyses suggest that GanB plays a primary role in cAMP/PKA signaling, whereas the SfaD-GpgA (G betagamma) heterodimer is crucial for proper activation of GanB signaling sensitized by glucose. In addition, the RGS protein RgsA is also involved in regulation of the cAMP/PKA pathway and germination via attenuation of GanB signaling. Genetic epistatic analyses led us to conclude that all controls exerted by GanB(alpha)-SfaD(beta)-GpgA(gamma) on conidial germination are mediated through the cAMP/PKA pathway. Furthermore, GanB may function in sensing various carbon sources and subsequent activation of downstream signaling for germination.
Lafon
Anne
A
Unité Postulante Biologie et Pathogénicité Fongiques, INRA USC2019, Institut Pasteur, Paris, France.
Seo
Jeong-Ah
JA
Han
Kap-Hoon
KH
Yu
Jae-Hyuk
JH
d'Enfert
Christophe
C
D001233:Aspergillus nidulans / Q000187:drug effects / Q000235:genetics / Q000502:physiology*; D000242:Cyclic AMP / Q000502:physiology*; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism; D000431:Ethanol / Q000494:pharmacology; D005656:Fungal Proteins / Q000235:genetics / Q000502:physiology; D044385:GTP-Binding Protein alpha Subunits / Q000235:genetics / Q000502:physiology; D044387:GTP-Binding Protein beta Subunits / Q000235:genetics / Q000502:physiology; D044388:GTP-Binding Protein gamma Subunits / Q000235:genetics / Q000502:physiology; D017353:Gene Deletion; D005947:Glucose / Q000494:pharmacology*; D020962:Heterotrimeric GTP-Binding Proteins / Q000235:genetics / Q000502:physiology*; D006601:Hexoses / Q000494:pharmacology; D009154:Mutation; D020710:RGS Proteins / Q000235:genetics / Q000502:physiology; D015398:Signal Transduction / Q000235:genetics / Q000502:physiology; D013172:Spores, Fungal / Q000187:drug effects / Q000254:growth & development
D005656:Fungal Proteins; D044385:GTP-Binding Protein alpha Subunits; D044387:GTP-Binding Protein beta Subunits; D044388:GTP-Binding Protein gamma Subunits; D006601:Hexoses; D020710:RGS Proteins; D000431:Ethanol; D000242:Cyclic AMP; D017868:Cyclic AMP-Dependent Protein Kinases; D020962:Heterotrimeric GTP-Binding Proteins; D005947:Glucose